IV Lepidoptera
This order of insects is known popularly by the names of Butterfly and Moth. Linnæus gave them the name of Lepidoptera, meaning insects with scaly wings (λεπις, a scale; and πτερον, a wing). They are to be found in great numbers in all parts of the world. All the insects contained in the order are, in their perfect state, remarkable for the elegance of their shape, the rapidity and airiness of their flight, and the multiplicity and beauty of their colours. Before they arrive at this perfect state, the Lepidoptera have to undergo three complete transformations. They leave the egg in the larva or caterpillar state; they pass next to the state of pupa, or chrysalis; they then assume, after a variable time, their final or perfect form. We will study them in their three different states in succession.
When the winter has stripped the leaves off the trees, the Lepidoptera are seen no more; but as soon as the leaves begin to show themselves on the trees and shrubs, this tribe of the insect race again makes its appearance. Caterpillars of all kinds are gnawing at the leaves, even before they are fully developed. Many of them have just emerged from the eggs which the perfect insects had laid at an earlier period; others have passed the winter in this state.
When they come out of the egg the young caterpillars are in shape more or less elongated and cylindrical. Their body is composed of twelve segments, or rings. In front is the head; then come three segments, on which are the front legs, and which constitute the thorax; the other segments constitute the abdomen. The head is formed of two scaly parts. It is often very deeply hollowed out on its upper side, and divided into two lobes, which contain in the angle formed by their separation the different parts of the mouth. The head is uniform, rarely having, so far as our cater pillars are concerned, any protuberance; but in the tropical species it is often armed with prickles, spikes, and extraordinary appendages. They are provided with six small simple eyes, isolated from each other. The mouth is armed laterally with a pair of very solid horny mandibles, articulated by means of vigorous muscles, and moving horizontally. It is the function of the mandibles, as with the jaws, to divide the creature’s food. On the middle of a broad under-lip one may perceive a little elongated tubular organ, pierced with a microscopic orifice. This organ is the spinning apparatus, which the animal uses in fabricating the threads which it will one day require. It is a tube composed of longitudinal fibres. It presents only one orifice, cut obliquely, and capable of applying itself exactly to the body on which the larva is placed. From the contractile nature of this organ and the form of its orifice, combined with the faculty the insect possesses of moving it in all directions, result the great differences we observe in the diameter and form of the threads.
The external organs of the trunk and abdomen are the legs, the spiracles, and various occasional appendages. The legs are of two different kinds. The one, to the number of six, attached by pairs to the trunk, are covered with a shiny cartilage, and armed with hooks. These are the true legs. Fig. 94 represents, after Réaumur’s “Mémoire sur les Différentes Parties des Chenilles,” 36 the scaly legs of the caterpillar of the Gipsy Moth. The others are membranous, fleshy, generally conical or cylindrical, contractile, and taking, according to the will of the animal, very different forms. Fig. 95 represents, after the same Memoir of Réaumur’s, the different forms of the membranous legs of the silkworm caterpillar. This plate gives a sufficiently good idea of the shape of these organs, and of the hooks, circular or semi-circular, with which they are furnished.
In Fig. 96 are represented, after the same author, two membranous legs of a large caterpillar, of which the hooks of the feet are fastened into a branch of a shrub.
Caterpillars have from two to ten false legs, the scaly legs being always six in number. The pro-legs, as the fleshy ones are called, are divided into hinder and intermediate. The former are two in number; the intermediate are rarely more than eight in number.
In the caterpillars which have the full number of legs—that is to say, sixteen—there are two empty spaces, where the body has no support: the one between the legs and the pro-legs, formed by the fourth and fifth segment; the other, between the intermediate pro-legs and the anal legs, formed by the tenth and eleventh ring.
The variations which caterpillars present, so far as the number and situations of their pro-legs are concerned, are the following:—
The greatest number among them have ten pro-legs; others have only eight; others only six—these may be called semi-loopers; others only four, one pair being situated on the last ring, and the other on the ninth, as in the case of looper caterpillars. And, lastly, there are others which have only two pro-legs.
The various forms, numbers, and positions of these organs, produce great differences in the mode of locomotion of caterpillars. Those provided with ten or eight membranous legs have in walking only a very slight undulating motion. Their bodies are parallel to the plane which supports them. They can walk very quickly; but their steps are short and quickly repeated. Others, on the contrary, in proportion as the number of their false legs diminish, and the spaces between the legs increase, walk in a more irregular and quaint manner.
If the reader will glance at Fig. 97, taken from Réaumur’s “Mémoire sur les Chenilles en général,”37 which represents a looper caterpillar, with four membranous legs, he will see that there is a considerable space between the posterior legs and the first pair of pro-legs, along which the body has no points of support. If one of these caterpillars, lying quiet and at full length, determines to walk, in order to take its first step (Fig. 98) it begins by humping its back, curving into an arch that part which has no legs, and finishes by assuming the position seen in Fig. 99. In the former position it has its two intermediate legs against the posterior legs, and, in consequence, it has brought forward the hinder part of its body, a distance equal to the interval of the five segments which separate them. There it hooks on by its intermediate and hind legs. Then it has only to raise and straighten the five rings which had formed the loop, and to advance its head to a distance equal to the length of five segments. The step is thus made, the caterpillar making the same movements in taking the second and following steps.
This sort of gait has gained for them the name of Geometers, because they seem to measure the road over which they travel. When they make a step, they apply the part of their body which they have just curved up to the ground, in exactly the same way as a land surveyor applies his chain to it.
These looper caterpillars cannot shorten nor lengthen their segments at will, as other caterpillars, but only bend their bodies. There are many species whose bodies are cylindrical, stiff, and of the same colour as bark. Their attitudes deceive even the close observer. They embrace the stem of a leaf or twig with their hinder and intermediate legs, whilst the rest of their body, vertically elevated, remains stiff and immovable for hours together. Fig. 100 shows the caterpillar of the Canary-shouldered Thorn (Eugonia alniaria) in this strange position. Now, this is a feat of strength which the most skilful of our acrobats, ordinary and extraordinary, which all the Leotards of the present day, and those who are to succeed them, can never accomplish. With such a persistency, this caterpillar can sustain its body in the air for a considerable time, in all the positions imaginable, between the vertical and the horizontal, and downwards again in any incline from the horizontal to the vertical. “If one considers,” says Réaumur, “how far we are from having in the muscles of our arms a force capable of supporting us in such attitudes as these, we must own that the power of the muscles in these insects is prodigious.”
We will not dwell now on the variableness of the length of the body of caterpillars; on the fleshy appendages which are to be observed on them; on the hairs which either beautify or render them hideous, according to the fancy of the observer; nor on the various colours with which they are decorated. We will notice these various characteristics when giving the history of some species of remarkable Lepidoptera.
Many caterpillars are solitary; others live in companies more or less numerous, either when young, or during the whole of their existence.
With the exception of a great number of moths, which live at the expense of our furs, or woollen stuffs, and leather or fatty matters, all caterpillars feed on plants. From the root to the seeds, no part of the vegetable is safe from their attacks. The greatest number of the species, however, prefer the leaves. Those of the most acrid and poisonous are no more spared than those of the most harmless plants. There are caterpillars which eat the leaves of the Euphorbia, or spurge, for instance.
“I wished to try,” says Réaumur, “the milk of this plant on my tongue. It produced hardly any effect upon it at first; but after a quarter of an hour I found my mouth on fire, and it was a heat which reiterated garglings with water during many hours in succession could not quench. This continued till the next day. The heat passed successively from one part of my mouth to another. I, however, saw many of my caterpillars drinking greedily the great drops of milk which were at the end of the broken stem I had presented to them.”
Is it not extraordinary that there are caterpillars which live on the nettle?—that they eat the leaves of this plant, armed as it is with stinging bristles, which cause such smarting and itching to the skin, and produce blisters upon it.
It has often been said that each plant has its own peculiar species of caterpillar. All we can say is, that a certain number of vegetables only suit certain caterpillars. The species which eat roots are few; those which live in the interior of stalks or stems which they feed on are numerous, and those which nourish themselves on the pulp of fruits are rare. In general, after the leaves, the caterpillars prefer the flowers: in this they certainly do not show bad taste. Their growth is more or less rapid, according to the species, according to the nourishment they take, and according to the season of the year. Those whose food is succulent grow more rapidly than those which have for their food dry gramineous plants and coriaceous lichens. Most of them eat at night, and remain during the day motionless, and as it were in a state of torpor; others are so voracious that they are constantly eating. This voracity is indeed sometimes surprising. Malpighi has observed that a silkworm often eats in a day mulberry leaves equal to its own weight. How could we provide our horses and oxen with provender, if they required each day their own weight of hay and grass? There are even some caterpillars which are still more voracious than that. Réaumur weighed several caterpillars of a species which lives on the cabbage, and gave them bits of cabbage-leaves which weighed twice as much as their bodies. In less than twenty-four hours they had entirely consumed them. In this space of time their weight increased one-tenth. Fancy a man whose weight is 180 lbs. eating in one day 360 lbs. of meat, and gaining 18 lbs. in weight! Caterpillars eat by the aid of two jaws or mandibles so broad and solid that, considering the smallness of the insect, they are equivalent to all the teeth with which large animals are furnished. It is by the alternate movement of these mandibles that the caterpillars devour the leaves with so much greediness and ease.
“A caterpillar, when it wants to gnaw the edge of a leaf,” says Réaumur, “twists its body in such a way that at least one portion of the edge of this leaf is passed between its legs. These legs hold fast that portion of the leaf which is to be cut by the insect’s jaws (Fig. 101). To give the first bite the caterpillar elongates its body, and carries its head as far forward as possible. The portion of the leaf which is between the open jaws is cut through the instant the teeth meet each other; the bites succeed each other quickly; there is not one, or scarcely one of them, that does not detach a bit, and each bit is swallowed almost as soon as cut off. At each fresh bite the head approaches the legs in such a way that during the succession of bites it describes an arc; it hollows out the portion of the leaf in a segment of a circle, and it is always in this order that it gnaws it.”
But there is a phenomenon in the life of caterpillars which we ought to point out, and which has attracted the attention of the most illustrious observers. All caterpillars change their skins many times during their life. It is not, indeed, enough to say that they change their skins; the skins or cases they cast are so complete that they might be taken for entire caterpillars. The hairs, the case of the legs, the claws with which the legs are provided, the hard and solid parts which cover the head, the jaws—all these are found in the skin which the insect abandons. What an operation for the poor little animal! This labour is so enormous, so troublesome, that one cannot form a just idea of it. One or two days before this grand crisis, the caterpillar leaves off eating, loses its usual activity, and becomes motionless and languid. Their colour fades, their skin dries little by little, they bow their backs, swell out their segments. At last this dried-up skin splits below the back, on the second or third ring, and lets us have a glimpse of a small portion of the new skin, easily to be recognised by the freshness and brightness of its colours.
“When once the split has been begun,” says Réaumur, “it is easy for the insect to extend it; it continues to swell out that part of its body which is opposite the slit. Very soon this part raises itself above the sides of the split; it does the work of a wedge, which elongates it; thus the split soon extends from the end or the commencement of the first ring as far as the other side of the end of the fourth. The upper portion of the body which corresponds to these four rings is then laid bare, and the caterpillar has an opening sufficiently large to serve it as an egress through which it can entirely leave its old skin. It curves its fore part, and draws it backwards; by this movement it disengages its head from under its old envelope, and brings it up to the beginning of the slit; at once it raises it, and puts it out through this slit. The moment afterwards it stretches out its fore part and lowers its head. There now remains for the caterpillar nothing but to draw its hinder part from the old case.”
This excessively laborious operation is finished in less than a minute. The new livery which the caterpillar has just put on is fresh and bright in colour. But the animal is exhausted by its fast, and the efforts which it has made. It requires a few hours in which to regain its equilibrium, and at the same time its former activity and voracity.
Having attained its full development, the caterpillar ceases to eat, as at the approach of a moult, it empties its intestinal canal by copious ejections; it loses its colours, and becomes dull and livid, and thus prepares itself to enter a new phase of its existence.
Some, when about to transform themselves into chrysalides, suspend themselves to foreign bodies. Others spin a cocoon, composed of silk and other substances, which secures them against the attacks of their enemies and the action of the atmosphere. Those which suspend themselves can be divided under two heads, according to the mode of their suspension:—1. Those which suspend themselves perpendicularly by the tail. 2. Those which, after having fixed themselves by the same part, suspend themselves horizontally, by means of a silk thread passed round the body.
To understand the difficulty which the first of these operations presents, we must consider the problem which the caterpillar has to solve. In this problem there are two unknown quantities to be discovered. Firstly, the caterpillar must suspend itself firmly; and secondly, the pupa, having no communication with the object which supports it, must be suspended in the same manner. This problem is difficult, apparently impossible, to solve. It is only by watching these insects at work that one can discover the wonderful mysteries of their lives. Swammerdam, Valisnieri, and other observers who have studied insects, had not, however, observed the manœuvres of caterpillars in this curious phase of their existence. It is to Réaumur again that science is indebted for the most charming and valuable observations on this point. He got together a great number of caterpillars of the small Tortoise-shell Butterfly (Vanessa urticæ), black prickly caterpillars which are common on the stinging-nettle, where they live in companies, and suspend themselves by the tail. When the time approaches at which the caterpillars of this species ought to undergo their transformations, they usually leave the plant which had up to that time served them as food. After having wandered about a little, they select some convenient spot, where they hang themselves up head downwards (Figs. 102, 103).
In order to hang itself in this way, the caterpillar begins by covering, with threads drawn in different directions, a pretty large extent of the surface of the body against which it wishes to fix itself. After having covered it thus with a kind of thin cobweb, it adds different layers of threads on a small portion of this surface, in such a manner that the upper one is always smaller than that upon which it is laid. In this manner a small hillock of silk is formed, the tissue of which is not at all compact. It resembles an assemblage of loose or badly interwoven threads. The membranous feet of the caterpillar are armed with hooks of different lengths, with the aid of which it suspends itself. By alternately contracting and elongating its body, it pushes its hindermost legs against the hillock of silk, presses against it the hooks of its feet, so as to get them better entangled, and lets its body fall in a vertical position.
It remains hanging thus, often for twenty-four hours, during which time it is occupied in a difficult task, that of splitting its skin. In order to effect this, it incessantly curves and recurves its body (Fig. 102), until at last a split appears on the skin of the back, and through this split emerges a part of the body of the chrysalis. This acts as a wedge, and little by little the split widens from the head to the last of the true legs, and beyond them. Then the opening is sufficient to allow of the chrysalis drawing out its anterior portion from the envelope, which it immediately does. To set itself entirely free, the chrysalis lengthens and shortens itself alternately (Fig. 105). Each time that it shortens itself, and when it consequently distends the part of its body which is outside the old skin, that part acts against the edges of the slit, and gradually pushes the old skin upwards. Thus the caterpillar skin ascends, its plaits are pushed nearer and nearer together, and it is soon reduced to a packet so small that it covers only the end of the tail of the chrysalis (Fig. 106).
But here comes the culminating point, the most difficult part of the operation. The chrysalis, which is shorter than the caterpillar, is at some distance from the silky network to which it must fix itself; it is only supported by that extremity of the caterpillar’s skin which had not been split open. It has neither legs nor arms, and yet it must free itself from this remaining part of the skin, and reach the threads to which it is to suspend itself.
The supple and contractile segments of the chrysalis serve for the limbs which are wanting to it. Between two of these segments, as with a pair of pincers, the insect seizes a portion of the folded skin, and with such a firm hold that it is able to support the whole of its body on it. It now curves its hinder parts slightly, and draws its tail entirely out of the sheath in which it was enclosed. It then reposes for an instant only, for it has not yet finished the laborious operation of its deliverance. It must free itself entirely from the dry skin which surrounds the extremity of its body.
The insect curves the part which is below its tail in such a manner that that part can embrace and seize the packet to which it holds on. It then gives to its body a violent shock, which makes it spin round many times on its tail, and that with great rapidity. During all these pirouettes the chrysalis acts against the skin; the hooks of its legs fray the threads, and break them or disentangle themselves from them. Sometimes the threads do not break at once. Then the animal recommences its revolutions in an opposite direction, and this time it is almost certain to succeed. Réaumur, however, saw a chrysalis which, after having tired itself in vain in its endeavours to get entirely free of its old skin, despairing of ever being able to manage it, abandoned it where it was so solidly fixed. We represent (Fig. 107), rather magnified, the chrysalis arrived at its final state, and suspended to a branch of a tree by a network of silk. 38
We come now to the mode of suspension employed by those caterpillars, which, after having fixed themselves by the tail, strengthen the support by means of a small silk cord passed round their body.
It is again to Réaumur, that indefatigable observer of the habits of insects, that we go for the details of this manner of suspension. According to Réaumur, these caterpillars make and put on this belt in three different ways. But of these three ways the simplest, and the least liable to meet with accident, is that employed by the larva of the Cabbage Butterfly (Pieris brassicæ). When the time for its metamorphosis is only a few days distant, one may observe this caterpillar engaged in stretching threads on different parts of the case in which it is confined. It then chooses a spot, which it covers entirely with threads, some more compact than the others, and disposed in layers, which cross each other in different directions. These threads form a thin white cloth, against which the belly of the caterpillar and later that of the chrysalis are applied. Very soon we see a small hillock of silk rising. The caterpillar hooks itself on to this by the claws of its hinder feet, and sets to work to secure itself.
To understand this process, it suffices to know that after having lengthened its body to a certain point, this caterpillar can turn back its head on to its back, and reach to the fifth ring, having its three pairs of true legs in the air. But without putting the caterpillar into such an unnatural position, let us take it in a position in which it is simply bent sideways in such a manner that its head, with the thread-spinning apparatus, which is below, can be applied opposite and pretty near to one of the legs belonging to the first pair of membranous legs. Our caterpillar begins by fixing on this point a thread, which is the first of those that are intended to tie it up securely.
“This thread,” says the illustrious author of the “Mémoires pour servir à l’Histoire des Insectes, “must pass over the caterpillar’s body, and be attached by its other end near the leg corresponding to that near which the first end was fastened. To spin the thread the proper length, and at the same time to fix it in its proper place, the caterpillar has only to bring round its head to the fifth segment. The thread will be drawn from the spinning apparatus as the head advances over half the circumference of the circle which it has to describe; and when it has described this, there will only remain for it to secure the second end of the thread against the support. Thus the head, which was at first placed against one of the legs, advances little by little on the outline of the fifth ring as far as to its middle (Fig. 108). It is the facility the caterpillar has of reversing its body that enables it to make its head perform this journey, in proportion as it moves it over the circumference of the ring, it twists its body. And at last, when it has brought it over the top of the segment, its body is exactly folded in two; it draws it little by little from this situation by bending towards the other side, and by causing its head to pass gently over the last quarter of the circle. At last the caterpillar finds itself bound on the second side; the head rests on the thread-covered plane, and the insect fixes the second end of the thread.”
It has only to repeat the same manœuvre as many times as there are threads wanted to make a strong band. But each thread embraces the head, or rather the lower part of the head, for it knows how to make each thread it spins glide into the bend or crease of its neck by a little movement of its head. It must disengage its head from under the band, not a difficult operation. It causes it to slide along the threads near one of the places where they are fixed, and it is then in the position indicated by the foregoing engraving (Fig. 109).
About thirty hours after the caterpillars have succeeded in making themselves fast, they have completed their transformation into chrysalides (Fig. 110), where the chrysalis of the above-mentioned caterpillar is seen in two different positions, and held by the same band which first supported the caterpillar.
Those caterpillars which construct cocoons make them of silk and other substances. These cocoons are, for the most part, oval or elliptical, sometimes boat-shaped, and ordinarily white, yellow, or brown in colour. The threads may very slightly adhere together, or be closely united by a gummy substance with which the caterpillar lines the interior of the cocoon, and which it expels from the anus. Some cocoons are composed of a double envelope, others are of a uniform texture. Some are of a tissue so close that they entirely hide the chrysalis contained within; others form a very light covering, through which the chrysalis can be easily perceived (Fig. 111).
Among caterpillars that make a very slight cocoon, some, as the Catocalas, gather together two or three leaves into a ball, to protect them. Others strengthen their cocoons, and render them opaque by adding earth or other substances, often obtained from their own bodies. Some, after having spun their cocoon, cast forth through the anus three or four masses of a matter resembling paste, which they apply with their head to the inside of the cocoon, and which, drying quickly, becomes pulverulent. Others employ for the same purpose the hairs with which their bodies are covered.
The larva of Acronycta aceris (Fig. 113) is covered with tufts of yellow hair. Réaumur made these caterpillars work under his own eye in glass vases. They make the layer which is to form the exterior surface of their shell, or cocoon, of pure silk, and when it is thick enough, tear out their hair, now from one place, now from another. But we will leave the illustrious observer to relate this operation himself, which must without doubt be painful to the poor animal:—
“Its two jaws are the pincers the caterpillar uses in seizing a portion of one or other of the tufts of hair; and when it has seized it, it tears it out without much difficulty. It at once places this against the tissue it has already commenced, in which it entangles it at first simply by pressure; it fixes it then more securely by spinning over it. It does not leave off tearing out its hairs till it has entirely stripped them off. When the caterpillar has taken between its jaws and torn out a whole tuft of hair, the head carries it and deposits it on some part of the lower surface of the cocoon; but it does not leave the hairs of such a large parcel together. The next moment one sees its head moving about very quickly; then taking a portion of the hairs from the little heap, it distributes them about on the neighbouring parts of the cocoon. If one opens one of these shells before the caterpillar has become a chrysalis, the larva, which is quite naked, and which was only known by its hair, can be no longer recognised.”
The caterpillar of the Tiger Moth, or Woolly Bear, called by Réaumur Marte or Herisson (Chelonia caja, Fig. 116), is covered with long inclined hairs. This caterpillar also makes use of its hairs for strengthening the tissue of its cocoon; but whether it feels the pain more acutely than the former, or whether it would suffer more, it does not tear out its hairs. It adopts another system; it cuts them. The caterpillar is then enveloped on all sides in its hair, which is to serve in the construction of its cocoon.
Another species uses its hairs in the composition of its cocoon; but it adopts an entirely peculiar way of tearing them out, when the tissue of its cocoon has become a species of network of pretty closely packed rings. Réaumur one day saw one part of the cocoon bristling with hairs. These were the hairs of a part of the back of the caterpillar, which it had pushed through the rings of its cocoon. The caterpillar then moved about as if rubbing this part of its back successively in opposite directions against the interior surface of the cocoon. In this way the hairs were very soon torn out and kept retained in the rings of the cocoon. This cocoon is then bristly inside, and does not at all suit the future chrysalis, which does not like to be touched by any but smooth surfaces. The caterpillar then works with its head, to lay the hairs along the interior surface, and to keep them down by threads, which it draws over them. At another time Réaumur saw a small hairy caterpillar, which appeared to live on lichens, using its hair in another way. It tore them out to make its cocoon, but it was not to lay them down and work them into a tissue. It set them straight up like the stakes of palisades, on the circumference of an oval space, in which it was placed. Shut up within this palisade, it spun a light white web. This web supports the hairs, causing the greater part of them to curve at their upper extremity, in such a manner as to form a sort of cradle.
It remains for us now to speak of the caterpillars that make their cocoons of silk, together with other materials. Réaumur saw the Pimpernel caterpillar arranging and sticking together the leaves of that plant, and spinning underneath them a thin cocoon of white silk (Fig. 119).
Some caterpillars make their cocoons on the surface of the earth, and even with earth. These cocoons are spherical or oblong. Their exterior is more or less well shaped, but their interior is always smooth, polished, shining like moistened earth, worked up together into a kind of paste, and carefully smoothed out. This cocoon is besides lined with a covering of silk of variable thickness. The shell is not made of earth alone; threads of silk may be seen in it, crossing each other, and binding together the particles of earth.
These subterranean workers do not allow their proceedings to be easily observed. Réaumur was fortunate enough to be able to notice their skill in the construction of their shells or cocoons. The Cucullia verbasci (Fig. 120) makes itself a thick and very compact cocoon of the form of an egg (Fig. 121). Réaumur took one of these out of the ground before it is fortified. He tore it partially open, and placed it in a glass vase containing sand, but the poor insect was not long in repairing the disorder caused by the rough hand of our naturalist. It only took four hours to restore its cocoon to its former state.
“It began,” says Réaumur, “by coming almost entirely out, and left only its hinder part within. It moved its head forwards as far as was necessary to enable it to seize a particle of earth. As soon as it had got its load, it re-entered the interior of the cocoon. It deposited the grain of earth, and came out again immediately, as it did at first, to pick up another grain, which it carried likewise into the interior of the cocoon. This operation it continued for more than an hour.... The provision of materials being got together, the caterpillar now devoted his whole attention to working them up. It began by spinning over one part of the edges of the opening. After having put over this a small band of very loose web, the caterpillar’s head left the opening, the insect went right back again into its cocoon, and the head returned to the opening loaded with a little grain of earth, which it entangled in the silky threads. It then entangled in them two or three, or a greater number of grains, according to the quantity of threads it had spun. It bound them into these with other threads, after which it drew threads over the edges of another part. By thus going round the whole rim of the opening, and by carrying and fixing the grains of earth in the threads which were the last stretched over the opening, it rendered its diameter smaller and smaller.”
It was by working with its head that our mason gave to the new wall of its cocoon the necessary curvature. It was interesting to know how, as it could no longer put out its head, it could stop up the orifice.
“It knew how to change its manœuvres. When the opening was reduced to a circle of only a few lines in diameter, it drew threads from a point on the circumference to another on the other side.... Thus the opening was covered in with a rather open network.... As soon as this web was finished, it got a grain of earth (which it had laid by until it was wanted), brought it up, placed it against the web, and by pushing and pressing it, made it pass through the web until it reached the exterior, and so in succession the whole of the web was covered with grains of earth.... It was not satisfied with rendering the exterior of this place exactly like the rest of the shell; it fortified it thoroughly; it added to it, one after another, layers of grains of earth, till it was as solid and as thick as the rest.”
The larva of Pyralis corticalis, which is found on oak trees in the month of May, shows to what a point these little insects carry their industry in the construction of their cocoons, in the choice of their materials, in their manner of working them up, and in the forms they cause them to assume. Réaumur one day saw this caterpillar on a small branch, between two triangular appendages (Figs. 122, 123). This was the beginning of a cocoon. Each triangular blade was composed of a great number of small, thin, rectangular plates, taken from the bark of the twig. The caterpillar detached with its jaws a small band of bark, and fitted it on, and adjusted it with admirable precision against the edge already formed. It then fixed it securely with silk threads. Réaumur saw this caterpillar work and erect in this way a large blade during an hour and a half.
“When one sees,” he says,39 “an insect which, to construct a cocoon, begins by collecting together an infinite number of small plates of bark in order to compose of them two flat triangular blades; which, to gain its end, takes means that seem so roundabout, although they are the most suitable and the quickest it could adopt, one is very much tempted to consider such an insect, when one sees it thus acting, possessed of reason.”
These two blades are at last transformed into a regular cocoon. The little animal, which is at the same time architect, cabinet-maker, and weaver, arranges it in such a way as to form a hollow cone, which it only remains for it to shut. Réaumur calls this sort of cocoon or shell, la coque en bateau, the boat-shaped cocoon. Some caterpillars weave cocoons of the same form with pure silk.
To bring this subject to an end, we will mention the industry of the Puss Moth (Dicranura vinula), and that of a small Tinea, which eats the barley stored away in our granaries.
The larva of the puss moth employs in the construction of its shell the wood of the tree on which it has lived. It bites it up, and mixing it with a glutinous fluid which it secretes from its mouth, reduces it to a sort of paste, which it then uses in the formation of an envelope, of such hardness that a knife can hardly cut into it.
The Tinea lines the interior of a grain, of which it has previously devoured the contents, with a coating of silk, and divides it thus into two different chambers. In one of these it is to change into a pupa; in the other it places its excrement. And so the little careful architect constructs its house in such a manner as to find in it tranquillity, cleanliness, and comfort.
When caterpillars have not within their reach the materials they are in the habit of employing, like good workmen, they content themselves with what they can get. Réaumur reared a caterpillar which formed its cocoon of pieces of the paper of which the box was made in which it was imprisoned.
What an extraordinary condition! what a strange phase of vitality does the chrysalis present to us—a being occupying the middle state between the caterpillar and the perfect insect! How little does it resemble that which it previously was, and what it will become! In appearance it is scarcely a living being; it takes no nourishment, and has no digestive organs; can neither walk nor drag itself along, and hardly bends the joints of its body. The outside skin of the chrysalis appears to be cartilaginous; it is generally smooth, although some species have hairs scattered over their bodies.
We distinguish in chrysalides two opposite sides. The one is the insect’s back, the other its under side. On the upper part of the latter (Fig. 124) we perceive various raised portions, formed and arranged like the bands round the heads of mummies; the back is plain and rounded in a great number of pupæ; but a great many others have on the upper part, along the edges which separate the two sides, little humps, eminences broader than they are thick, ending in a sharp point (Fig. 125).
The head of the angular pupæ terminates sometimes in two angular parts, which diverge from each other like two horns (Fig. 126). In some other cases they are curved into the form of a crescent. These appendages sometimes give to the pupa the appearance of a mask, especially as an eminence placed on the middle of the back is rather like a nose, and the small cavities may represent the eyes (Fig. 125).
The colours of angular pupæ attract our attention. Some are superbly tinted; they appear to be wrapped in silk and gold. Others have only spots of gold and silver on their belly or their back. All, however, have not this remarkable splendour, not these metallic spots. Some are green, yellow, and spotted with gold. Generally they are brown. Réaumur has shown that this golden colour is not due, as was thought for a long while, to colouring matter, but to a little whitish membrane, placed under the skin, which reflects the light through the thin outer pellicle, in such a manner as to produce the optical illusion which imparts to the robe of the chrysalis the golden hues of a princess in grand costume. All is not gold that glitters, Réaumur proves literally, in the case of chrysalis. 40
Let us add that the chrysalis remains thus superbly dressed as long as it is tenanted, but loses its colour as soon as the butterfly has quitted it.
The cone-shaped pupæ belong to the twilight and night-flying Lepidoptera, and to those butterflies whose caterpillars are onisciform, or in shape resembling a wood-louse. They are generally oval, rounded at the head, and more or less conical at the lower end. Their colour is generally of a uniform chestnut brown.
What a mystery is that which is accomplished in the transition from the chrysalis to the perfect state! Those great changes from the larva state to that of the pupa, and from the pupa to that of the imago, are accomplished with such rapidity, that the phenomena were looked on as sudden metamorphoses, like those related in mythology. It has been thought also that there was in these changes from one state to another a sort of resurrection. There is here neither sudden metamorphosis, nor, as we will show, resurrection. In fact, the chrysalis is a living being; it indeed shows its vitality by exterior movements. Under the old skin of a caterpillar about to moult, under the envelope which is soon to be cast off, the new integuments are being prepared.
Some days before the moult, split the caterpillar’s skin, and you will find the skin which is to take its place already beneath. If, some days before the transformation of the caterpillar into a chrysalis, it is dissected, the rudiments of wings and antennæ may be discovered. If a chrysalis is examined on the outside, all the parts of the future insect can be distinguished under the skin: the wings, the legs, the antennæ, the proboscis, &c.; only, these parts are folded and packed away in such a manner that the chrysalis can make no use of them. It could not, moreover, make use of them on account of their incomplete development. Fig. 127 shows, after Réaumur,41 a chrysalis magnified and seen from its lower side, on which we observe:—a, the wings; b b, the antennæ; t, the trunk or proboscis.
There is a moment when these parts, pressed one against each other, and as it were swathed up like a mummy, are very easily seen, for they are, as we may say, laid bare. This moment is that in which the pupa has just quitted the caterpillar’s skin. It is then still soft and tender. Its body is moistened with a liquid, which, drying rapidly, becomes opaque, coloured, and of a membranous consistency. The result is that the parts which did not cohere in the least when the chrysalis made its first appearance, are fastened together, so that although they could at first be seen, through a layer of transparent fluid, they are now hidden under a sort of veil or cloak. It is necessary to seize then the moment of the birth of the chrysalis, to observe it accurately.
On examining the pupa before the liquid which pervades these parts has had time to dry, it resembles the perfect insect. All the exterior parts which belong to the imago can be distinguished. One recognises the head, which is then resting on the thorax; the two eyes and the antennæ (Fig. 128), which are brought forward like two ribbons; the wings also brought over the thorax, but these are separated artificially in the drawing we have given after Réaumur; 42 and lastly in the space left between the wings, the six legs, and the body of the insect.
To sum up: the pupa, when it approaches the period for being hatched is only a swaddled butterfly. Directly it has strength enough to rid itself of its wrapping, the insect frees itself from its fetters; it flies away, brilliant and free, and its many-coloured wings glitter in the sun.
The duration of the pupa state is variable, according to the species and the temperature. Réaumur placed in a hot-house, in the month of January, some pupæ which, in the ordinary course of things, would not have been hatched till the month of May, and a fortnight afterwards the imagos had appeared. On the other hand, he shut up some pupæ in an ice-house during the whole of a summer, and thus retarded their being hatched by a whole year. The influence of the temperature on the period of emerging, and, consequently, the influence of the seasons on the length of this period, are completely brought to light by these experiments. 43
We will now see how the insect delivers itself from the last skin. To quit the pupa case is not so laborious an operation as it was for the same insect to quit the caterpillar’s skin. This is because the pupa case is drier; it does not adhere to every part of the body, and is brittle. Those insects which are enclosed in a cocoon free themselves of the pupa envelope in the cocoon itself. To witness the last operation, the cocoon may be opened, and the pupa drawn out of it with care. If it is then placed in a box, the metamorphosis may be observed. To study this last evolution more at his ease, Réaumur covered a large extent of the wall of his study with pupæ of the Vanessa polychloros and other species.
When the parts of the body of the insect have attained a certain degree of solidity within the envelope, it has no great difficulty in making the thin and friable membrane which surrounds it split in different places. If it even distends itself or moves, a small opening will be made in the dried skin. If the movements persist, the opening increases in size, and very soon allows the imago to emerge.
It is on the middle of the upper part of the thorax that the envelope begins to split. The split extends over the middle of the forehead and back. The pieces of the thorax open, separate themselves from the other parts to which they were fixed, and the insect can take advantage of the opening which is made, and escape. Little by little also it advances its head. The head is the first out of the old skin, and the insect sets itself entirely free.
This occupies rather a long time; for we must remember that, under the pupal envelope, its legs, its antennæ, its wings, and many other parts, are enclosed in special cases. These peculiar circumstances show that the animal has much trouble and must employ some time in setting free all the parts.
At last our prisoner has come out of its narrow cell, and is delivered from its old covering. What poet can describe to us the sensations of this charming and frail creature which has just risen from the tomb, and for the first time is enjoying the splendid light of day, the radiant sky, and the flowers redolent with delicious perfumes, which are inviting it to kiss and caress them!
The wings strike one most. They are very small at the time of birth.
Fig. 129 represents, after Réaumur, 44 a moth at the moment in which it has just emerged from the pupa. But at the end of a short period the wings become developed; only they are wrinkled, as Fig. 130, given by Réaumur, represents.
Réaumur having taken between his fingers a very short wing of a butterfly which was just hatched, drew it about gently in all directions. He succeeded thus in giving it the whole extent it would have assumed naturally. According to Réaumur the wing of a butterfly just born, which appears so small, is really already provided with all its parts, only it is folded and re-folded on itself. He supposes that what his hands did to lengthen the butterfly’s wings, is done naturally by the liquids which are contained in the insect which has just emerged, and whose wings are no longer confined in their cases. At the time of its birth the wings are flat and thick; as they grow, little by little they spread themselves out and become curled up. When they are completely developed and flattened the wings become firm and hard imperceptibly, and this firmness extends at the same time to the whole of the body.
Figs. 131 and 132, borrowed, like the preceding, from the 14th Memoir of Réaumur (sur la transformation des chrysalides en papillons), show the states through which the wings of the same moth pass, before they are thoroughly developed.
Those pupæ enclosed in cocoons free themselves entirely or in part from their old skin, in the shell itself; but the imago is still a prisoner. It has broken through a first enclosure; it must open itself a way through the second. How does it manage to bore through the often very solid walls of this second prison, so as to regain its liberty? Réaumur states that in the Lackey Moth (Bombyx neustria) the head is the only instrument of which the insect makes use in opening a passage, the compound eyes then acting like files. These files cut the very fine threads of which the cocoon is composed, and as soon as the end of the cocoon is pierced through, the insect uses its thorax like a wedge, to enlarge the hole. It very soon manages to get its two front legs out, fixes itself by them on to the outside, and little by little emerges from its prison.
Who does not admire the extraordinary splendour, the vivacity, the prodigious variety of colours of these brilliant inhabitants of the air? Some amateurs have devoted to the purchase of certain butterflies large sums of money. “Diamonds,” says Réaumur on the subject, “have perhaps beauties no more real than those of a butterfly’s wings; but they have a beauty which is more acknowledged by the world in general, and which is more recognised in commerce.” The essential character of butterflies and moths makes them very easily recognisable among all other insects. All have four wings, which are covered with scales, that communicate to them the brilliant colours with which they are decorated. It is these scales which adhere to the fingers when we seize one of these charming creatures.
For a long time this dust was thought to be formed of very small feathers, but Réaumur showed that it is composed of little scales. Their form varies singularly, as we may see in Fig. 133, borrowed from the Memoirs of Réaumur, 45 which represents the different forms of the scales which cover the wings of Lepidoptera. M. Bernard Deschamps has closely studied them. According to this naturalist, they are composed of three membranes, or plates, superposed one on the other, of which the first is covered with granulations of a rounded form, which give to these scales their splendid and varied colours; the second plate is covered with silk, forming sometimes curious designs; the third plate, viz., that which is applied to the membrane of the wing, has the peculiar property of reflecting colours the most brilliant and the most varied, although the surface of the scales visible to the eye is often dull and colourless.
“Supposing,” says M. Bernard Deschamps, “that a painter was possessed of colours rich enough to represent on canvas with all their splendour, gold, silver, the opal, the ruby, the sapphire, the emerald, and the other precious stones which the East produces, that with these colours he formed all the shades which could result from their combination, one might affirm without the chance of contradiction, that he would have none of these colours and of their various shades, whatever might be the number, which could not be discovered by the microscope on part of the scales of the Lepidoptera, which Nature has been pleased to conceal from our gaze.”
Each of these scales adheres to the membrane of the wing by a small tube, which is solidly fixed to it. Réaumur has called our attention to the admirable arrangement of these scales, which are disposed like those of fish, that is to say, in such a manner that those of a row shall partially overlap those in the following one.
In Fig. 134, representing a portion of the wing of the Saturnia pavonia major, magnified, which we borrow from Réaumur’s Memoir, the scales are arranged in rows; isolated scales, and the points where other scales were fixed before they were taken off, are represented.
The membranous frame which supports the coloured scales of butterflies and moths is well worth a moment’s consideration. It consists of two membranes intimately united by their interior surfaces, and divided into many distinct parts by horny, fistulous threads, more or less ramified, which seem intended to support the two membranes mentioned above, and which branch out from the base to the edge of the wing. Their number, counting from the exterior edge, is not always the same in the upper and lower wings. It varies from eight to twelve.
With its large and light wings, the butterfly can fly for a long time. But this flight is not in the least regular; it is not made in a straight line. When the insect has to go some distance, it flies alternately up and down. The line it takes is composed of an infinity of zig-zags, going up and down, and from right to left. This irregularity of flight saves the little insect from falling a prey to birds. “I saw one day with pleasure,” says Réaumur, “a sparrow which pursued in the air a butterfly for nearly ten minutes without being able to catch it. The flight of the bird was nevertheless considerably more rapid than that of the butterfly, but the butterfly was always higher or lower than the place to which the bird flew, and where it thought it would catch it.”
But let us leave the wings to pass on to the other parts of the butterfly. These other parts are the thorax or chest, the body or abdomen, and the head.
The thorax is solidly put together, so as to bear the movements of the wings and legs. These latter are composed, as in other insects, of five parts: the coxa, the trochanter, the thigh, the shank, and the tarsus.
Many butterflies have all their six legs of equal length. In others, the two fore legs are very small, and are not suited for walking. In others, again, they are rudimentary, being deprived of hooks, very hairy, and applied on to the front of the breast.
This difference of structure may be seen in Figs. 135 and 136, one of which represents, after Réaumur, a leg unsuited for walking, very hairy, and terminated in a sort of brush resembling the tail on a tippet; and the other a leg furnished with hooks.
The abdomen has the form of an elongated, or—in the majority of species—an almost cylindrical oval. It is composed of five segments, each formed of an upper and a lower ring, joined together by a membrane. The first are larger than the others, and generally overlap the edges, which gives to this part of the body the power of dilating considerably.
We must dwell longer on the head. It is generally rounded, compressed in front, longer than it is broad, and furnished with fine or scaly hairs. The important organs of which this part is the seat are the eyes, the antennæ, the palpi, and the proboscis or trunk.
The eyes are more or less spherical, surrounded by hairs, and composed of innumerable facettes. Colours are seen on these as various as those of the rainbow. But the colour which serves as a base to all, is black in some, grey in others; then again there are different gold or bronze colours of the greatest splendour, inclining sometimes to red, sometimes to yellow, sometimes to green. On the compound eye of a butterfly as many as 17,325 facettes have been counted. Simple eyes, or stemmata, are moreover observed in certain species, and are generally more or less hidden by scales.
The antennæ are situated near the upper rim or border of each eye. Réaumur has pointed out six principal shapes. One terminates in a little knob, and belongs to the butterflies. The others are variously shaped, and belong to the moths. Some are prismatic, or like beading. And lastly, others are shaped like feathers. We represent, in Fig. 137, the different forms of the antennæ, which Réaumur collected together in plates 8 and 9 of his fifth Memoir. 46
The palpi are four in number, two maxillary and two labial. The first are generally excessively small; one can only ascertain their existence by the aid of a strong magnifying glass: the second are in general very apparent, straight, cylindrical, covered with scales, and formed of three joints, of which the last is often very small and sometimes very pointed. They also sometimes bristle with stiff or silky hairs.
The trunk is placed exactly between the two eyes. As long as the butterfly does not want to take nourishment, the trunk remains rolled in a spiral. Some are so short, that they scarcely make one turn and a half or two turns; some larger sized make three turns and a half or four turns; lastly, some very long are curled as many as eight or ten times.
This is how the butterfly makes use of its trunk: When fluttering around a flower, it will very soon settle on or quite close to it. The trunk is then brought forward entirely or almost entirely unrolled; very soon afterwards it is almost straightened, then directed downwards, and plunged into the flower. Sometimes the insect draws it out a moment after, curves it, twists it a little, and sometimes even curls it partially up. Immediately it straightens it again, to plunge it a second time into the same flower. It repeats the same manœuvre seven or eight times, and then flies on to another flower.
This trunk, of which the butterfly makes such good use, is composed of two filaments more or less long, horny, concave in their interior surfaces, and fastened together by their edges. When cut transversely, one sees, according to Réaumur, 47 that the interior is composed of three small rings. Consequently, there are three canals in the trunk: one central, the other two lateral (Fig. 138). Are all these three used to conduct the juice of flowers into the butterfly’s body? Réaumur has made some very interesting observations on this subject, by observing a moth which was sucking a lump of sugar whilst its portrait was being taken.
“I held in one hand,” says Réaumur, “a powerful magnifying glass, which I brought near to that part of the trunk I wished to examine; I was sometimes half a minute, or nearly a minute, without perceiving anything, after which I saw clearly a little column of liquid mounting quickly along the whole length of the trunk. Often this column appeared to be intersected by little balls, which seemed to be globules of air which had been drawn up with the liquid.
“This liquid ascended thus during three or four seconds, and then ceased. At the end of an interval of a greater number of seconds, or sometimes after an interval as short, I saw some fresh liquid mounting up along the trunk. But it was straight up the middle of the trunk that it seemed to ascend.
“The Author of Nature has given to insects means of working, which, though very simple, we cannot divine, and which often we are not able even to perceive. Whilst I was observing the trunk of our butterfly, between the columns of liquid which I saw ascending, there were, but more rarely, times when I saw, on the contrary, liquid descending from the base of the trunk to the point. The descending liquid occupied half or two-thirds of the tube. It was no longer difficult to perceive how the butterfly is able to nourish itself on honey, the thickest syrup, and even the most solid sugar. The fluid it sends down is probably very liquid; it drives against the sugar, moistens, and dissolves it. The butterfly pumps this liquid up again when it is charged with sugar, and conducts it along as far as the base of its trunk, and beyond it.”
The life of the perfect insect is generally very short. Like nearly all other insects, they die as soon as they have propagated their species. The female lays her eggs, which vary in shape, on the plant which is to nourish her progeny. The colour is also very various, and passes through all sorts of shades. At the moment they are laid, many are covered with a gummy substance, insoluble in water, which serves to stick them on the plant.
In some species the mother lays her eggs on the trunks of trees, and covers them with down or with the hairs which clothe her abdomen, so as to preserve them from cold and damp. She may also hide them entirely under a whitish foamy substance. Some do not lay more than a hundred eggs; others lay some thousands.
To bring the history of the Lepidoptera to an end, it only remains for us to give a sketch of their classification, and to point out some species remarkable, either on account of their beauty or their utility.
We see during the day butterflies flying in our gardens, in meadows full of flowers, or in the alleys of woods. Towards evening, at the sombre hour of twilight, the stroller is sometimes surprised to see pass near him large moths, with a heavy and unequal flight; or, if we go into a garden on a beautiful calm summer’s night, bearing a light, we see a crowd of moths flying from all parts towards it.
It is on account of these different hours at which the Lepidoptera show themselves, that naturalists for a long time divided them into diurnal, crepuscular, and nocturnal. This division was simple, convenient, and seemed founded on Nature. Unfortunately, the night fliers of the old authors do not all fly by night: some species, classed by the old naturalists among the crepuscular, or nocturnal, show themselves in the very middle of the day, seeking their food in the hottest rays of the sun. In the regions near the poles they appear during the day, and in other countries they are more or less friends of the twilight.
So as not to multiply methodical divisions, we will confine ourselves to classing the Lepidoptera into two sections.
The first section contains those which fly during the day, which have club-shaped antennæ, and which have their four wings entirely free, and standing perpendicularly 48 when the insect is at rest. They are called Butterflies, or Rhopalocera. This section is divided into a number of families, which comprise many genera. We will content ourselves with calling the attention of the reader to some of the most remarkable of these groups, and to those species which, either on account of their beauty or abundance, strike, or ought to strike, the attention of every one.
In the family of the Papilionidi, we will mention the genera Papilio, to which belong the Swallow-tailed Butterfly (Papilio machaon), Papilio podalirius, &c., and Parnassius, of which we will notice Parnassius Apollo, and Parnassius Mnemosyne.
The swallow-tailed butterfly is found plentifully in the fens of Cambridgeshire, and Norfolk and Suffolk, and very commonly in the environs of Paris. It is seen from the beginning of May till towards the middle of June; then from the end of July till September. It frequents gardens, woods, and, above all, fields of lucerne. It is easily taken when settled, particularly at sunset.
This is one of the largest and the most beautiful of the European butterflies. The wings are variegated with yellow and black; the eyes, antennæ, and trunk are black. The body is yellow on the sides and underneath, and black above. The front wings have rounded edges; the hind ones, on the contrary, are notched, and one of these notches is prolonged into a sort of tail. The first are black, spotted and striped with yellow; the second have their upper part and middle yellow, with some touches only of black. Near the margin is a broad black band, dusted with blue; lastly, six yellow spots in the form of a crescent run along the border, and end in a magnificent eye of a reddish colour, bordered with blue.
The caterpillar of this species is large, smooth, and of a beautiful light green, with a transverse black band on each ring. These bands are sprinkled with orange spots. It lives on the fennel, carrot, and other Umbelliferæ. If teased, it thrusts from the first ring after the head a fleshy, orange-coloured tentacle. The chrysalis, attached to a stalk of grass, is sometimes light green, sometimes greyish.
In the low Alps, on the plains near the environs of Digne and Barcelonette, is found in the months of May and July the Papilio Alexanor (Fig. 141), and in Corsica and Sardinia is found the Papilio hospiton, a rare species, nearly related to our swallow-tailed butterfly, but which we will here content ourselves with mentioning.
The Papilio podalirius (Fig. 142) is in form very analogous to Papilio machaon. It is of a rather pale yellow colour, marked with black, as if singed. The lower wings have tails longer and narrower than those of the latter, and are magnificently ornamented with blue crescent-shaped spots and an orange-coloured eye bordered below with blue. This beautiful species is not rare at Montmorency, at Ile-Adam, and at St. Germain. It is said to have been taken in England, and is called the scarce Swallow-tail, but its capture is considered as very questionable. It appears for the first time at the end of April, and for the second in July and August. The Parnassius Apollo (Fig. 143), is a beautiful butterfly, which appears in June and July, and is found commonly enough in the Alps, the Pyrenees, and the Cévennes. Its wings are of a yellowish white. The upper part of the fore wings presents five nearly round black spots; the base and the costa, or front edge, of these wings are sprinkled with black atoms. The upper part of the hind wings presents two eyes of a vermilion red, the inner border furnished with whitish hairs amply dotted with black, and marked towards the extremity with two black spots. The under part of the fore wings is very similar to the upper. But the under part of the hind wings presents four red spots bordered by black, forming a transverse band near the base. The body is black, furnished with russety hairs, and the antennæ white, with the club black.
The larva of the Apollo lives on saxifrages. To affect its transformation it surrounds itself with a slight network of silk in which are confined one or more leaves. This caterpillar is thick, smooth, cylindrical, and covered with small slightly hairy warts, and ornamented on the first ring with a fleshy tentacle in the shape of a Y. The chrysalis is conical, sprinkled over with a bluish efflorescence resembling the bloom on a plum. The Parnassius Mnemosyne is found in the month of June in the mountains of Dauphiné, in Switzerland, Sicily, Hungary, Sweden, and in the Pyrenees.
In the family of the Pieridi we will mention many species remarkable in different ways, such as Pieris cratægi, the black-veined White, Pieris brassicæ, the Cabbage Butterfly, Pieris napi, Pieris callidice, Anthocharis cardamines, the Orange-tip, Rhodocera (Gonepteryx) rhamni, and Colias edusa, or Clouded-yellow. Pieris cratægi is white both above and below; the veins only of the wings are black, and become a little broader at the edge of the upper wings. These black veins on a rather transparent white ground make this butterfly resemble a gauze veil, hence its French name, le gaze. It flies in spring and summer in meadows and gardens, but is not generally common in England. In the first volume of his “Travels in the North of Russia,” Pallas relates that he saw insects of this species flying in great numbers in the environs of Winofka, and that he at first took them for flakes of snow. The Pieris cratægi fixes itself at sunset on flowers, where it is easily taken by the hand. During the day, on the contrary, it is difficult to catch. The larva, black at first, afterwards assumes short yellow and white hairs, but it varies much. They live in companies, under a silky web, in which they pass the winter. The leaves of the hawthorn, the sloe, the cherry tree, and of many other fruit trees, serve them for food. The pupa, yellow or white, and sometimes of both colours with little stripes and spots of black, is angular and terminated in front by a blunt point.
The Pieris brassicæ (Fig. 144), or Cabbage Butterfly, is perhaps the commonest of all butterflies. From the beginning of spring till the end of autumn one sees it flying about everywhere, in the gardens, sometimes near and almost in the interior of towns. It is of a dull white, spotted and veined with black, and it can be seen at a long distance, when flitting from flower to flower, in a meadow or garden. And so children wage desperate war against this flying prey. The pursuit of the cabbage butterfly through the alleys of parks, along the outskirts of woods, or on the green turf of meadows, is the first joy and the first passion of children in the country.
The caterpillar (Fig. 145) is of a yellowish green, or rather greenish yellow, with three yellow longitudinal stripes separated by little black points, from each of which springs a whitish hair. It lives in groups on the cabbages in gardens, and on many other Cruciferæ. It is so voracious that it consumes in a day more than double its own weight, and, as it multiplies very quickly, commits great ravages in the vegetable garden. Its pupa (Fig. 145) is of an ashy white, spotted with black and yellow.
The Pieris rapæ, or Small White Butterfly, differs but little from the preceding except in size. The caterpillar, which lives on the cabbage, turnip, mignonette, nasturtium, &c., is green, with three yellow lines. It does not do these much harm. In France it is called le ver du cœur (the heartworm), because it penetrates in between leaves pressed closely together.
The Pieris napi (Fig. 146), the Green-veined White, is very like the two preceding, but the wings, the lower one especially, have underneath broad veins, or bands, of a greenish colour. The Pieris callidice, the wings of which are white spotted with black, is common in the Alps of France, in Savoy and Switzerland, and in the Pyrenees. Its caterpillar lives near the regions of perpetual snow, on small cruciferous plants.
The Orange-tips have, in the males, the extremity of the upper wings of a beautiful orange yellow. The rest of the wings is white in the only British species (Fig. 147), which is to be seen in meadows from the end of April till the end of May, and sulphur-coloured in some other species.
One species, extremely common, and which appears with but short interruption from the beginning of spring till the end of autumn, is the Brimstone Butterfly (Rhodocera [Gonepteryx] rhamni). The wings are a lemon yellow, with an orange-coloured spot in the middle of each, and the front border terminated in a series of very small iron-coloured spots. The body of the butterfly is black with silvery hairs.
The Colias edusa, or Clouded-yellow, so called from the colour of the upper part of its wings, is not uncommon in meadows and fields in early autumn throughout Europe. The upper side of the wings is of a marigold yellow; the upper ones having towards the middle a large spot of black. At the extremity of each wing is a broad black band, continuous in the case of the male, interrupted by yellow spots in the female. The back of the body is yellow; the legs, as well as the antennæ, rosy.
The family of the Lycænidæ comprises a great number of species, some of which we will mention.
The Theclæ, or Hair-streaks, which the French call Petits Porte-queues, on account of the tails which grace the hind margin of the hind wings, inhabit woods, their larvæ feeding, according to the species, on the birch, the oak, the plum-tree, the bramble, &c.
The Thecla betulæ (Fig. 148), or Brown Hair-streak, is somewhat rare in this country.
The Purple Hair-streak (Thecla quercus, Fig. 149), which Geoffroy calls the “Porte-queue bleu à une bande blanche,” is not rare in woods; but it is very difficult to catch, as it flies nearly always by couples at the tops of trees. We still further represent here the Black Hair-streak (Thecla pruni, Fig. 150), and the Green Hair-streak (Thecla rubi, Fig. 151).
In the meadows are found the Copper Butterflies; butterflies with wings of a bright, tawny colour, with black marks on the upper side. Such is the Polyommatus (Lycæna) phlæas (Fig. 152), which is very common from the end of May until late in the autumn. The upper part of the wing is coppery, spotted with black, the under side of a grey colour, sprinkled with small eyes, and bordered by a zone of tawny spots. Linnæus counted forty-two little black eyes on the under side of the wings.
We also figure Polyommatus (Lycæna) virgaureæ (Fig. 153), and Polyommatus (Lycæna) gordius (Fig. 154), neither of which occurs in this country.
In the meadows, the gardens, and the lucerne and clover fields, are found the charming Blue Butterflies, the wings on the upper side, in the majority of instances, blue in the case of the males, brown in the females.
They comprise the genus Lycæna, or, as it is frequently called, Polyommatus,49 though that name is now generally given to the preceding. We will content ourselves here by giving drawings of a few species of the genus, namely, the Lycæna (Polyommatus) Corydon, or Blue Argus (Fig. 155), which is not uncommon wherever there is chalk, in May and August; the Lycæna (Polyommatus) battus, or Brown Argus (Fig. 156), which does not occur here; the Lycæna (Polyommatus) ægan, which flies about our sandy heaths.
The caterpillars of this genus, as also those of the preceding, are broad and flat, resembling wood-lice, with very short legs, and are very slow in their movements.
In the numerous family of the Vanessidæ are placed the beautiful species known as the large and small Tortoise-shell, the Peacock, &c.
The large Tortoise-shell Butterfly (Vanessa polychloros, Fig. 158) has the wings of a tawny colour above, and of a blackish brown below, with darker spots, bordered by a black band, with a stripe of yellowish colour running down the middle. It is found in July and September on the oak, the elm, the willow, and many fruit trees.
The larva (Fig. 159) is bluish or brownish, with an orange-coloured lateral line, bristling with yellowish hairs. The chrysalis, which is angular, and of a red tint, is ornamented with golden metallic spots.
We give here a drawing of the small Tortoise-shell (Vanessa urticæ, Fig. 160), which resembles the preceding, but is smaller. Its caterpillar, bristly, blackish, with four yellowish lines, lives in companies on the nettle. The Peacock Butterfly (Vanessa Io, Fig. 161) is very easily recognised by the peacock’s eyes—to the number of four, one on each wing—which have gained for it the name it bears. The eye on the upper wings is reddish in the middle and surrounded by a yellowish circle. That on the lower ones is blackish, with a grey circle round it, and contains bluish spots. The upper part of the wings is of a russety brown, the under part blackish. This Vanessa is met with in the woods, in lucerne fields, and in gardens. Its spiny caterpillar is of a shiny black with white dots, and lives in companies on nettles. The chrysalis, at first greenish, then brownish, is ornamented with golden spots.
The Vanessa Antiopa (Fig. 162), one of the greatest of entomological rarities in England, is not very common in the woods about Paris, but it is frequently found in the environs of Bordeaux, and, above all, at the Grande Chartreuse (in the department of Isère). The Parisian collectors go as far as Fontainebleau in pursuit of this beautiful species, with angular wings, of a dark purple black, with a yellowish or whitish band on the hind border and a succession of blue spots above it. The caterpillar is black, and bristly, with red spots. It lives in companies on the birch, the aspen, the elm, and different kinds of willows. The pupa is blackish, sprinkled with a bluish powder, and has ferruginous-coloured dots. The butterfly, which emerges from the chrysalis in July and August, is found, after hybernation, at the end of February and until May. It flies very rapidly, and is very difficult to catch.
The Red Admiral Butterfly (Vanessa Atalanta, Fig. 163) has bands of vermilion colour on the upper side of its wings, which are black above, and variegated beneath with different colours. The caterpillar is bristly and blackish, with a succession of spots of lemon-colour on its sides. It lives in solitude on the stinging-nettle (Urtica dioica). Its chrysalis is blackish, with golden spots. This magnificent insect is common at the end of summer, and easy to catch. If missed once it comes back again almost immediately, and almost alights on the net of the collector.
The Painted Lady (Vanessa [Cynthia] cardui, Fig. 164) owes its vernacular name to the beauty of its colours. The upper wings are covered above with tawny spots, rather cerise coloured towards the interior, and with white spots on the hind margin towards the tip of the wing; the whole on a lightish ground. The lower wings are of a reddish tawny colour with many black spots, a circular row of which borders the wing. The caterpillar is bristly, brownish, with yellow lateral broken lines. It lives in solitude on many species of thistle, on the artichoke, the milfoil or yarrow, &c. It makes for itself a web, rather like a spider’s nest, and lives therein. The chrysalis is greyish, with numerous golden dots. The perfect insect shows itself almost without interruption, from spring till autumn. It flies rapidly, and in certain seasons is abundant.
The Vanessa (Grapta) C. album (Fig. 165), or Comma Butterfly, is common in parts of England. Above, its wings are tawny, spotted with black. Below, they are more or less brown, with different tints, and sometimes a little blue. On the under side of the lower wings is a white spot of the form of a C. “This spot,” says old Geoffroy, “caused this butterfly to have the name of gamma given to it, and its colour of Diable enrhumé (sic), as also the singular cut of its wings, has caused it to be called by others Robert le Diable.” Its caterpillar lives on the nettle, the honeysuckle, the currant, the hazel, and the elm. It is of a reddish brown, with a white band on the back. Réaumur calls it the Beadle, comparing it to the church beadles, who usually dress in glaring colours.
The brilliant Vanessæ, of which we have just briefly described some remarkable species, have been the cause of superstitious terror. This must at first sight seem incredible, but it has arisen thus: When they have just quitted the pupa, a red-coloured liquid drops from them. If a great many butterflies are hatched at the same time, and in the same place, the ground becomes, as it were, sprinkled with drops of blood. Hence the origin of some of those pretended showers of blood, which, at different periods, have terrified the ignorant, too much imbued with religious superstitions.
At the beginning of the month of July, 1608, one of these supposed showers of blood fell on the outskirts of Aix, in Provence, and this rain extended for the distance of half a league from the town. Some priests of the town deceived themselves, or, desirous of turning to account the credulity of the people, did not hesitate to attribute this event to Satanic agency. Fortunately, a learned man, M. de Peiresc, who was not only well versed in the knowledge of ancient literature, but who was, moreover, familiar with the natural sciences, discovered that a prodigious multitude of butterflies were flying about in the places which were thus miraculously covered with blood. He collected some chrysalides and put them into a box, and letting them hatch there, observed the blood-like liquid, and hastened to make it known to the friends of the miraculous. He established the fact that the supposed drops of blood were only found in cavities, in interstices, under the copings of walls, &c., and never on the surface of stones turned upwards; and proved by these observations that they were drops of a red liquid deposited by the butterflies.
However, in spite of the reassuring remarks of the learned Peiresc, the people in the outskirts of Aix continued to feel a genuine terror at the sight of these tears of blood which stained the soil. Peiresc attributes to this same cause some other showers of blood related by historians, and which took place about the same season. Such was a shower which was supposed to have fallen in the time of Childebert, at Paris, and in a house in the territory of Senlis. Such again was a so-called bloody shower which showed itself towards the end of June, during the reign of King Robert of France. Réaumur points out the large Tortoise-shell as being the most capable of spreading these sorts of alarms, founded on a deplorable ignorance and the spirit of superstition.
“Thousands,” says he, “change into pupæ towards the end of May or the beginning of June. Before their transformation they leave the trees, often fastening themselves to walls, and, making their way into country-houses, they suspend themselves to the frames of doors, &c. If the butterflies which come out of them towards the end of June or the beginning of July were all to fly together, there would be enough of them to form little clouds or swarms, and consequently there would be enough to cover the stones in certain localities with spots of a blood-red colour, and to make those who only seek to terrify themselves, and to see prodigies in everything, believe that during the night it had rained blood.”
In the family of Nymphalidæ, we will first mention the White Admiral (Fig. 166). The upper side of its wings is of a dark brown, almost black, traversed in the middle by a white band divided into spots very close to each other. The lower part of the wings is ferruginous, with a band and spots of white, as on the upper, besides which it has a double hinder transverse row of black dots. These dots are followed on the hind wings by some white spots, and the whole of the inner margin is of a glossy ashy blue, with the base spotted with black. This butterfly is not rare in the month of July in woods in the south of England, where it flies round and settles upon the branches of the underwood. The caterpillar is of a delicate green, with a lateral white stripe, and rather bristly. It feeds on honeysuckle. The pupa is angular, of greenish colour, with golden spots.
The Limenitis camilla (Fig. 167), of which the black on the wings is shot with blue, is not found in England.
In the month of July the Apatura ilia (Fig. 168) and the Purple Emperor (Apatura iris), sylvan insects of strong flight, whose wings are beautifully shot with violet blue when examined in certain lights—the latter resembling Ilia, but wanting the eye-like spots on the front wings—are met with. Iris only is found in this country. Both species occur in the environs of Paris.
The Charaxes jasius (Fig. 169), which is found along the whole of the Mediterranean coast, has its lower wings terminated in two points, whence the peasants call this butterfly the Pacha with two tails. The upper part of its wings is of a brown colour of changing hues. The hind margin of the fore wings has along it a tawny band with a fine black line running round. The hind wings have their hinder margin black, and garnished with a little white fringe. The two tails are black, and the groove of the inner margin is of an ashy grey. The underneath of the wings is ferruginous, with spots of an olive brown set in a framework of white towards the base.
The caterpillar is green, and flat like a slug, with four yellow horns bordered with red (Fig. 170). It lives on the arbutus, a shrub common enough on the hills and mountains of the coast of the Mediterranean.
To the family of the Satyridi belongs the Erebia Euryale (Fig. 171), which is found in the month of July in sub-alpine regions; the Chionobas aello (Fig. 172), which is found in the Alps of Switzerland, of the Tyrol, and of Savoy, and which is common enough, in the month of July, on the summit of Montanvers, near the mer de glace; the Satyrus janira, or Meadow Brown (Fig. 173), which is very common, in the months of June and July, in woods and fields.
We now pass on to the second section of Lepidoptera.
It contains those whose flight in the majority of species is nocturnal or by twilight, but by day in some species. The antennæ are more or less swollen out in the middle or before their extremities, and, independently of that, sometimes prismatic, sometimes cylindrical, sometimes pectinated or indented. The body—which was small in comparison to the wings, and which was remarkably thin between the thorax and the abdomen in the first section of Lepidoptera—is in this section very much larger in proportion to the wings, and is not drawn tightly in between the thorax and the abdomen. The wings are horizontal or slightly inclined when the insect is at rest; the upper then cover the lower, which are generally comparatively short and kept back by a bridle on the first, in the case of the males only.
We will take the genus Sesia as the representative of the Sesiidæ. These singular insects have membranous wings, and resemble various species of Hymenoptera. The largest species is the Sesia apiformis (Fig. 174), that is, bee-like, which is found in this country, resting on the trunks of willows and poplar-trees, from the end of May till the middle of July. It resembles a hornet, and is of the same size and has the same colours; only they are not quite so bright. When this moth is just hatched its wings are ferruginous; but its scales, light and caducous, fall as soon as the insect begins to fly. The caterpillar, which lives in the trunks or roots of willows and poplar-trees, is of a yellowish colour. The pupa is long, of a brownish colour, enclosed in a cocoon composed of agglutinated saw-dust, the product of the caterpillar’s erosions.
In the middle of summer the meadows are frequented by moths, with brilliant black and velvety wings, marked with red, which fly heavily, and only for a short time together. They remain motionless during the great heat of the day. These are the Zygænæ, or Burnets, of the family of the Zygænidæ. The Ram Sphinx of Geoffroy, or the Six-spot Burnet Moth (Zygæna filipendulæ, Fig. 175), is common from the end of June till the beginning of August. Its legs, antennæ, head, and body are black and rather hairy; its upper wings are of a brilliant bluish green, with six spots of a beautiful red on each, bordered by a little green. The caterpillar is yellow, spotted with black; its cocoon is boat-shaped, with longitudinal furrows, and is straw colour (Fig. 176).
Next to Zygæna comes Procris, the species of which fly during the day in damp fields. We will mention particularly the Procris statices (Fig. 177), which is plentiful enough where it occurs between the middle of June and the middle of July, on the sides of hills. Its fore wings, antennæ, and the whole of its body, are of a blue green above. The same wings are of the same colour below, and the surfaces of the lower ones are of an ashy brown.
The Sphinges, that is, those species that form the family of the Sphingidæ, have received this general name from the attitude which their caterpillars often assume. Raising the fore part of the body, which attitude resembles the Sphinx of mythology, they keep for a very long time this state of immobility. They fly very rapidly and briskly, and only make their appearance for the most part after sunset. The caterpillars, which in this group are without hair, and have almost always a horn on the eleventh segment of the body, metamorphose themselves in the earth, without forming hard cocoons. The chrysalis are sometimes enveloped in a very slight shell, or cocoon, which when it exists is formed of particles of earth or of vegetable débris bound together by threads. This family comprises species generally remarkable for their size and beauty.
The genus Macroglossa contains some species which fly rapidly and for a long time together during the day. We will mention particularly the Humming-bird Sphinx (Macroglossa stellatarum). This moth (Fig. 178) has attracted the attention of all who have ever spent much time in a flower garden. In Burgundy the children call it bird-fly. In passing from one flower to another it has brisk and rapid movements, but it remains suspended in the air before each; it does not alight upon any, it is always flying, thrusting its long trunk the while into the corollæ of flowers, counterbalancing the action of its weight by the continuous vibration of its wings.
We will describe in a few words this robust inhabitant of the air, this charming bird-fly. The Macroglossa stellatarum shows itself during the whole of the fine season, and till the middle of autumn, in our climate. It often penetrates in the middle of the day into our houses, and knocking itself against the window-panes, falls an easy prey to children. Its front wings are of an ashy brown, of changing hues above, with three black, transverse, undulating lines. The lower, shorter than the others, are of a rusty-yellow colour. All the wings are yellowish below near the body, ferruginous in the middle, and of a dark brown at their extremities.
The body is long, brown, hairy, and terminating in a tuft of divergent hairs, reminding one of a bird’s tail. It is for this reason that it has been called by the French Sphinx Moineau, or Sparrow Sphinx. This resemblance is so great, that Mr. Bates, in his book on the Amazons, says he often shot species of this genus in mistake for humming-birds. The caterpillar of this remarkable Lepidopteron (Fig. 179) is of a pale green, with eight transversal rows of small white dots and four longitudinal rows, of which two are white and two yellowish. It has a dark blue horn, with an orange-coloured tip. It lives on different species of bed-straw, but by preference on the Galium mollugo. Before its metamorphosis, it encloses itself in a shapeless cocoon, made of the débris of leaves held together by threads, and placed on the surface of the ground. The pupa (Fig. 180) is of a light grey, sprinkled over with brown dots, and striped with black. Its skin is so thin and transparent that one can follow it through all the phases of transformation to the imago.
The genus Deilephila is composed of species whose flight is rapid, and after sunset. Such are the Deilephila euphorbiæ, the Oleander Hawk-Moth (Deilephila [Chærocampa] nerii), and the large Elephant Hawk-Moth (Deilephila [Chærocampa] elpenor).
The Deilephila euphorbiæ (Fig. 181) has the upper wings of a reddish grey, with three spots of greenish or olive colour along the costa, or front margin, and a broad black oblique band along the hind margin. The lower wings are red, with the base black, and a transverse black band towards the edge; they have, moreover, a large round white spot on the inside; beneath the wings are red, as also is the body, which is covered above with greenish hairs. This species is exceedingly rare here, but is plentiful on the Continent during the months of June and September.
The larva (Fig. 182) is one of the most remarkable of the genus on account of the splendour and the vividness of its colours, and appears to be covered with varnish. It has a number of small yellow dots very close to each other on a glossy black ground, which are ranged in circles. On each side of the body are two longitudinal rows of spots generally of the same colour as the dots, and a narrow band of carmine runs down the middle of the back, and a similar band, which is intersected by yellow, is to be seen above the legs. This caterpillar is almost always found on the Cyprus-leafed spurge. It is found first at the end of June. Generally the chrysalis passes through the winter, and the moth emerges in the following year.
The Deilephila (Chærocampa) nerii (Fig. 183), or Oleander Hawk-Moth, is a charming species almost peculiar to hot countries, where the shrub from which it derives its name grows spontaneously—that is to say, in Africa, in the southern parts of Asia, in Greece, in Spain, &c. Carried forward by its rapid flight, and assisted by atmospheric currents, these beautiful insects sometimes come accidentally into the countries of Central Europe. They have been met with many times in Paris, in the garden of the Luxembourg, where the oleander is cultivated under glass. But those which are hatched in the environs of Paris never reproduce their species, on account of the coldness of the climate. Both larva and imago—the former on periwinkle—have been found in the same locality.
The caterpillar of this species (Fig. 184) is one of those called by the French Cochonnes, because their two first rings, which are retractile and drawn back under the third when the insect is at rest, taper in such a way as to resemble the snout of a pig, hence the English name “Elephant,” when they change their place or are engaged in eating. It is of a beautiful green, with white stripes and dots on the sides, and marked on the third segment with two large spots like eyes, of an azure blue, encircled with black, and having white pupils. A short orange-coloured horn rises at the extremity of the body. A few days before its transformation, this caterpillar entirely loses its rich livery, it becomes brown on the back, and of a dirty yellow on the rest of its body, and constructs for itself a cocoon at the foot of the shrub on which it lived, with the débris of leaves fastened together with threads.
The cocoon contains a chrysalis (Fig. 185) of a hazel brown, delicately streaked with a darker brown, and with a very conspicuous black spot on each of its stigmata.
The Elephant Hawk-Moth (Deilephila [Chærocampa] elpenor, Fig. 186) is not rare during the month of June. Its fore wings are purple red, glossy above, with three bands of a light olive green, having at the base a small black spot. The inner margin is garnished with white hairs. The hind wings are of a dark rose colour above, with the base black, and the hind margin bordered with white. The four wings are rose coloured below, with the costa and the middle of an olive green; the upper ones have their interior border tinged with a blackish colour. The body is rose colour, with two longitudinal bands of an olive green over the abdomen, and five diverging lines of this colour on the thorax. The sides of the abdomen have along them a double series of yellowish points.
The caterpillar of this sphinx (Fig. 187) is of a dark brown, delicately striped with black. Two grey lines run down each side of its body, and on the fourth and fifth segments are two black eyes bordered by light violet. This caterpillar is found most often on certain kinds of Epilobium, but will also eat of the vine, fuchsia, and bed-straw. It must be sought in damp places, by streams and ponds, from the end of July till September. It constructs on the surface of the soil a shapeless cocoon with moss and dry leaves, which it fastens together with some silky threads. Its pupa (Fig. 188), of a yellowish brown, has short bristles on the rings of the abdomen. The caterpillar possesses in the highest degree the retractile power which has gained for certain species of this genus their popular names. The Privet Sphinx (Sphinx ligustri, Fig. 189) has its upper wings rather narrow, about two inches long, of a reddish grey, and veined with black above, with the middle of a dark brown, the inner margin with rose-coloured hairs, and the hind margin having two whitish flexuous lines running along it. The hind wings are of a rose tint, with three black bands. The wings are of a reddish grey below with a common black band. The abdomen has black and rose-coloured rings above, and in the middle a brownish band wholly divided by a black line.
This species is very common in all parts of Europe. One finds it in gardens from June to September. Of all the caterpillars of the genus Sphinx, this is the one which, by its attitude when in a state of repose, most resembles the sphinx of fable, from which the genus has derived its name. It is of fine apple green, with seven oblique stripes, half violet and half white, placed on each side of its body, and three or four small white spots beyond these stripes. The stigmata are orange, the head is green, bordered with black. The extremity of the body is surrounded by a smooth horn, black above, yellow below (Fig. 190). This beautiful caterpillar is not rare. It lives on a great number of trees and shrubs, but it is principally on the privet, the lilac, and the ash tree, that it must be looked for. Three or four days before it buries itself in the earth to change itself into a chrysalis, its beautiful colours grow dim. During the month of June and September is found the Convolvulus Sphinx (Sphinx convolvuli, Fig. 192), with brown wings, and with the abdomen striped with transverse bands alternately black and red. The caterpillar of this species, which presents a great number of varieties, lives on many kinds of Convolvuli, but particularly on the field species. It is generally rare here, but occasionally abundant.
It is to the genus Acherontia that a well-known moth belongs. We refer to the Death’s-head Moth (Acherontia atropos). It is the largest species of hawk-moth. This insect presents, roughly marked out in light yellow, on the black ground of its thorax, a human skull. This funeral symbol, joined to the plaintive cry which this moth emits when frightened, has sometimes inspired terror into the whole population of a country. The appearance of this moth in certain countries having coincided with the invasion of an epidemic disease, some thought they saw in this doleful sylph of the night the messenger of death. The Acherontia atropos plays a great part in the superstitions which are believed in by the country folk in England. One hears it said in country places that this ominous inhabitant of the air is in league with the witches, and that it goes and murmurs into their ears with its sad and plaintive voice the name of the person whom death is soon to carry off. In spite of its ominous livery, the Atropos does not come from Hades; it is no envoy of death, bringing sadness and mourning. It does not bring us news of another world; it tells us, on the contrary, that Nature can people every hour; that it was her will to console them for their sadness, to grant to the twilight and to the night the same winged wanderers which are at once the delight and ornament of the hours of light and of day.
This is the mission of science, to dissipate the thousands of prejudices and dangerous superstitions which mislead ignorant people.
This moth has the front wings of a blackish brown colour, having lighter irregular bands varied with brown and grey, above and below. On the middle of the front wing there is a well-defined white dot. The hind wings have two black bands, the upper narrower than the lower one; the rest of the wing is a fine yellow. The abdomen has likewise from five to six yellow and as many black bands; in the middle is a long blackish longitudinal band. This moth is not very rare, and may be found in autumn. Its flight is heavy, and, as we have said, the insect never flies till after sunset. If caught, or when teased, it utters a cry which is very audible.
The death’s-head hawk-moth would be a very inoffensive being if it did not make its way into bee-hives, in order to steal the honey, of which it is excessively fond. It is to no purpose that the bees dart their stings at the intruder, they only blunt them against its thick skin, and soon, terrified at its presence, disperse on all sides.
The caterpillar of the Acherontia atropos (Fig. 194) is the largest of all European caterpillars. It attains to as much as four and a half inches in length by eight lines in diameter. Its colour is lemon yellow, which changes into green on the sides and belly. From the fourth to the tenth ring inclusively it is ornamented laterally with seven oblique bands of an azure blue, which are tinted with violet, and bordered with white on the side. These bands joining together over the back of each segment resemble so many chevrons placed parallel to each other. The body is, moreover, dotted with black. At its extremity is a yellow horn, curved back like a hook, and covered with tubercles. The head is green, and marked laterally with a black stripe. It lives chiefly on the potato, and the Lycium barbarum, sometimes called the tea-tree, a shrub belonging to the Solanaceæ. It buries itself in the earth to change into a chrysalis (Fig. 195) of a bright chestnut brown.
We will mention still further, in the family of the Sphingidæ, three species of the genus Smerinthus, which fly heavily and by twilight.
The Lime-tree Hawk-moth (Smerinthus tiliæ, Fig. 196) has its upper wings grey with some shades of green, and moreover, in the middle of the wing an irregular band of a brownish green colour. The thorax, covered with hairs, is grey, with three green longitudinal bands. The abdomen is also grey. The moth flies heavily after sunset, and is found on the trunks of trees during the months of May and June. The larva (Fig. 197) is glaucous green dotted with yellow, and marked on each side with seven oblique lines of the same colours. Its wrinkly horn is blue above and yellow below. It is found on the lime and the elm. It buries itself at the foot of the tree on which it has fed to change into a chrysalis without making a cocoon.
We will content ourselves by here giving drawings of two other species of the same genus: the Eyed Hawk-Moth (Smerinthus ocellatus, Fig. 198), which is not rare during the months of May and sometimes August, the caterpillar of which lives on the leaves of willows, poplars, and fruit-trees; and the Poplar Hawk-Moth (Smerinthus populi, Fig. 199), whose caterpillar (Fig. 200) lives on the poplar, the aspen, and sometimes on the willow and birch.
The division of Bombycina contains the largest of moths, and at the same time species of a middle and small size. These moths take no nourishment, and live only for a short time—long enough to propagate their species. They rarely fly during the day, only showing themselves in the evening. The group is dispersed over nearly all parts of the world, and may be recognised by the antennæ generally being cut like the teeth of a comb in the males, by their thick, strong bodies, and, in the majority of cases, by their large head, by their wings more or less large, and by their heavy flight.
In the Bombycina are found the genera Sericaria, Attacus, Bombyx, Orgyia, Liparis, &c.
It is to the genus Bombyx that the silkworm belongs, that celebrated insect called by Linnæus Bombyx mori, a name which reminds us at the same time of its most ancient denomination, and of the mulberry tree, on which these caterpillars feed.
M. Guérin-Méneville has called the silkworm “the dog of insects,” for it has been domesticated from the most ancient times, and has become deprived of great part of its strength in the process. The moth of the silkworm can no longer keep its position in the air, or on the leaves of the mulberry when they are agitated by the wind. It can no longer protect itself, under the leaves, from the burning heat of the sun and from its enemies. The female, always motionless, seems to be ignorant of the fact that she has wings. The male no longer flies; he flutters round his companion, without quitting the ground. It ought, however, to be possessed in the wild state of a sufficiently powerful flight. M. Ch. Martins found that after three generations reared in the open air, the males recovered their lost power.
Before speaking of the different phases of the life of the silkworm and the rearing of this precious insect, we will notice the origin and progress of the silk trade, one of the most important branches of commerce in the South of Europe and in the East.
The native country of the silkworm is not better known than that of the greater number of plants and animals which form the staple of agricultural industry. Probably, however, it was China. It was certainly in this vast empire that long since the business of fabricating silk began. One reads the following in “L’Histoire générale de la Chine,” by M. Mailla:—
“The Emperor Hoang-ti, who lived 2,600 years before our era, wished that Si-ling-chi, his wife, should contribute to the happiness of his people; he charged her to study the silkworm, and to try to utilise its threads. Si-ling-chi caused a great quantity of these insects to be collected, which she fed herself in a place destined exclusively for the purpose; she not only discovered the means of rearing them, but still further the manner of winding off their silk and of employing it in the manufacture of fabrics.”
It may be asked, however, if the learned men who composed this recital did not collect under the reign of the emperor Hoang-ti all the events and all the discoveries whose dates were lost in the obscurity of the most remote periods of history. Is not the Empress Si-ling-chi a mythical person? a sort of Chinese Ceres, to whom, under the title of goddess of the silkworm, they then raised altars?
Here, at any rate, is how Duhalde50 analyses the recital of the Chinese annalists on the remarkable fact of the introduction of the silkworm and its rich products into the Chinese empire:—
“Up to the time of this queen (Si-ling-chi),” says he, “when the country was only lately cleared and brought into cultivation, the people employed the skins of animals as clothes. But these skins were no longer sufficient for the multitude of the inhabitants; necessity made them industrious; they applied themselves to the manufacture of cloth wherewith to cover themselves. But it was to this princess that they owed the useful invention of silk stuffs. Afterwards, the empress, named by Chinese authors, according to the order of their dynasties, found an agreeable occupation in superintending the hatching, rearing, and feeding of silkworms, in making silk, and working it up when made. There was an enclosure attached to the palace for the cultivation of mulberry trees.
“The empress, accompanied by queens and the greatest ladies of the court, went in state into this inclosure, and gathered with her own hand the leaves of three branches which her ladies in waiting had lowered till they were within her reach; the finest pieces of silk which she made herself, or which were made by her orders and under her own eye, were destined for the ceremony of the grand sacrifice offered to Chang-si. (Plate V.)
“It is probable,” adds Duhalde, “that policy had more to do than anything else with all this trouble taken by the empresses. Their intention was to induce, by their example, the princesses and ladies of quality, and the whole people, to rear silkworms: in the same way as the emperors, to ennoble in some sort agriculture, and to encourage the people to undertake laborious works, never failed, at the beginning of each spring, to guide the plough in person, and with great state to plough up a few furrows, and in these sow some seed.
“As far as concerns the empresses, it is a long time since they have ceased to apply themselves to the manufacture of silk; one sees, nevertheless, in the precincts of the imperial palace, a large space covered with houses, the road leading to which is still called the road which leads to the place destined for the rearing of silkworms, for the amusement of the empresses and queens. In the books of the philosopher Mencius, is a wise police rule, made under the first reigns, which determines the space destined for the cultivation of mulberry trees, according to the extent of the land possessed by each private individual.”
M. Stanislas Julien51 tells us of many regulations made by the Emperor of China, to render obligatory the care and attention requisite to rearing silk.
Tchin-iu, being governor of the district of Kien-Si, ordered that every man should plant fifty feet of land with mulberry trees. 52 The Emperor (under the dynasty of Witei) gave to each man twenty acres of land on condition that he planted fifty feet with mulberry trees.53 Hien-tsang (who ascended the throne in 806) ordered that the inhabitants of the country should plant two feet in every acre with mulberry trees.54 The first Emperor of the dynasty of Song (who began to reign about the year 960) published a decree forbidding his subjects to cut down the mulberry trees. 55
By all these means, according to the testimony of M. Stanislas Julien, the business of the fabrication of silk became general in China. This great empire soon furnished its neighbours with this precious textile material, and created for its own profit a very important branch of commerce.
It was forbidden, under pain of death, to export from China the silkworm’s eggs, or to furnish the necessary information in the art of obtaining the textile material. The manufactured article only could be sold out of the empire. It was thus that the Asiatic nations very soon understood silk; and that in many of their cities they applied themselves to weaving stuffs of this precious substance. The carpets and dyed stuffs of Babylon, mixed with gold and silk, enjoyed in ancient times an unparalleled renown. China was not, however, the only country that then furnished silk to the towns of Asia Minor. At a very distant period India sent by her caravans very considerable quantities of it. M. Émile Blanchard (of the Institute) remarks, however, that the tissues of India must be made of a different silk from that of China, that is to say, of a silk of some of those Bombyces of which the public has been told so much of late years, and of which we shall have soon to speak.
Silk commanded for centuries a prodigiously high price. In the time of Alexander its value in Greece was exactly its own weight in gold, and so it was very parsimoniously employed in silk tissues. These were so transparent that women who wore them were scarcely covered.
Silk was unknown to the Romans before Julius Cæsar. It was to him that Rome owed its acquaintance with this new material. He introduced it, moreover, in a singularly magnificent manner. One day, at a fête given in the Colosseum—a combat of animals and gladiators—the people saw the coarse tent of cloth, intended to keep off the rays of the sun, replaced by a magnificent covering of Oriental silk. They murmured at this gorgeous prodigality, but declared Cæsar a great man. The introduction of silk among the Romans was the signal for luxurious expenditure. The patricians made a great display with their silk cloaks of incalculable value; so that, from the time of Tiberius, the Senate felt itself called upon to forbid the use of silk garments to men. Examples of simplicity are sometimes set in high places; thus, the Emperor Aurelian refused to the Empress Severina so costly a dress.
The commerce in silk bore doubly hard upon Europe, both on account of the value of the material and of the great use which was made of it. Persia was the emporium, and had the monopoly of this merchandise. The Emperor Justinian I., who reigned at Constantinople from A.D. 527 to 565, tried all the means within his power of freeing his States from this ruinous tyranny, when a circumstance occurred, very fortunately for the national commerce, which brought about the introduction into Europe of sericulture, or the cultivation of silk.
Two monks of the order of St. Basil, in their ardour for the propagation of the faith, had pushed forwards into China. There they had been initiated into the operations which furnished the fabric so highly prized. On their return to Constantinople, and hearing of the project that Justinian entertained of depriving the Persians of the monopoly in silk, the two monks proposed to the Emperor to enrich his state by introducing the art of fabricating this material. The proposition was greedily accepted, and the two monks returned again to China, with the object of procuring the eggs of the insect. Having arrived at the end of their journey, they succeeded in getting possession of a quantity of silkworms’ eggs. They hid them between the knots of their sticks, and started back to their native country, without being once interfered with. Two years afterwards they re-entered Constantinople with their precious booty. 56 The larva were fed on mulberry leaves. Immediately afterwards began the rearing of the worms and the preparation of the silk, according to the instructions given by these courageous travellers. The first broods succeeded perfectly, and so plantations of mulberry trees were seen to multiply and spread through the whole extent of the Eastern Empire. It was, above all, in Southern Greece that this branch of industry assumed an immense importance. It was then the Pelopon nesus lost its old name, and was called the Morea, from the Latin name for “mulberry,” morus. 57
Constantinople and Greece, during centuries, furnished the whole of Europe with silkworms. This diffusion, however, was effected very slowly. The Greeks attached great importance to retaining the monopoly, and the emperor Justinian had caused to be established at Constantinople itself silk manufactories, where the most skilful artificers of Asia, who were forbidden to reveal the various processes to strangers, worked.
Towards the beginning of the eighth century the Arabs introduced the silkworm into Spain. But this industry remained confined within narrow limits. It was in fact not till after the twelfth century that sericulture began to spread throughout Europe. Roger, King of the Two Sicilies, possessing a navy that commanded the Mediterranean, employed it chiefly in making excursions and conquests. He ravaged Greece, and, not satisfied with the booty he carried away from that unfortunate country, wished still further to deprive them, for the good of his own kingdom, of the silk monopoly, the source of their riches. Roger carried away into Sicily and Naples a great number of prisoners, amongst whom were some weavers and men who had devoted themselves to the rearing of silkworms. In 1169 he established these workmen in houses adjoining his own palace at Palermo. There they dyed the silk of different colours, and mixed it with gold, pearls, and precious stones.
From Sicily the art of preparing silk spread over the rest of Italy. In 1204 the workers in silk constituted themselves into a syndicate at Florence. It is not, however, till 1423—more than two hundred years after the introduction of this branch of industry into Italy—that we find the first mention of the cultivation of the mulberry tree in Tuscany. In 1440 each Tuscan peasant was forced to plant at least five mulberry trees on the land he cultivated. In 1474 the commerce in silk fabrics with all parts of the world had become extremely prosperous at Florence. In 1314 the Venetian manufactures began to assume much importance. Three thousand workers in silk were then established in Venice.
Without dwelling longer on the propagation of the silk trade in Italy, let us pass on to its establishment in France. It was in 1340 that some French gentlemen, who had stayed some time in Naples, planted in Avignon the first mulberry trees. 58 According to Olivier de Serres, it was not introduced till much later into Dauphiné. It was not introduced into Alan, near Montelimart, till 1495, by the Seigneur Guyape de Saint-Aubain. 59 Louis XI. made great efforts to develop the silk trade in France, by inviting over Italian workmen; and they began under his reign to fabricate silks in Touraine and Lyons. Francis I. greatly developed the trade of Lyons. In 1554, under Henry II., the masters and men employed in the manufacture of gold, silver, and silk in Lyons were twelve thousand in number. Under Henry II. were planted the mulberry trees of Bourdezière, Tours, Chenonceaux, Toulouse, and Moulins. These plantations, however, were of very small extent. They were not the result of a general and truly popular effort; moreover, civil war came very soon, and turned men’s minds away from the isolated attempts of some few private individuals. Sericulture, in fact, did not assume any great importance in France till the reign of Henry IV.
This king saw with grief considerable sums of money leaving France each year for the purchase of raw silk or of silk stuffs. Two men marvellously furthered his project of encouraging the silk trade. One of these men was Barthelemy Laffemas, called Beausemblant. For a long time he had been writing memoir upon memoir, to demonstrate the advantages to be derived from the plantation of the mulberry tree in France; and he tells us that silkworms were then raised with success at Nantes, at Poissy, and even at Paris. The second supporter whom Henry IV. found in the propagation of sericulture was a man distinguished in a very different way from that of M. Laffemas. This was Olivier de Serres, the author of the “Théâtre de l’Agriculture;” he whom Henry IV. called his lord and master in agriculture. Olivier de Serres was the first among his countrymen who had published instructions regarding the cultivation of mulberry trees and the rearing of silkworms. Henry IV., who had noticed his writings, called him to Paris; and, on his solicitation, caused twenty thousand mulberry trees and a great quantity of silkworms’ eggs, of which a distribution was made over the whole of France, to be imported from Italy. From that moment, sericulture was propagated rapidly in the Cévennes, in Provence, in Languedoc, in Touraine, and many other provinces. Mulberry trees were planted at Fontainebleau, in the royal park of Tournelles, and even in the Tuileries, where an Italian lady, named Julle, reared silkworms for Henry IV.
Notwithstanding this great impulse, sericulture dwindled away on the death of that king. It received a fresh impulse under Colbert, the great minister, who succeeded in creating the spirit of commerce and trade in France. New manufactories were established, and plantations of mulberry trees formed in many of the provinces. All this progress was suddenly brought to a standstill by the iniquitous revocation of the Edict of Nantes, which deprived France of her leading commercial men. Driven from their own country, the Protestant families of the Cévennes established abroad silk manufactories, the fabrics of which rivalled those of French production.
In the eighteenth century the intendants of the provinces tried, but with very slight success, to give a fresh impetus to sericulture in France. The Abbé Boissier de Sauvages published, about 1760, some works, which prove him to have been a patient observer, an accurate reasoner, and a clever rearer of silkworms. Boissier de Sauvages is the father of modern silk-culture. During the first Revolution, men’s minds were occupied with graver subjects than the cultivation of the mulberry tree. But, on the return of peace, they got to work again on all sides. In 1808, the minister Chaptal estimated the weight of the cocoon harvest at between five or six thousand kilogrammes; whilst the invention of the Jacquard loom gave an immense impulse to the weaving of silk stuffs. Amongst those who introduced and benefited the art of sericulture, we must not forget Dandolo. Dandolo, who was born at Venice in 1758, and died in 1819, was the first who, at the beginning of this century, applied himself seriously to the amelioration of the processes employed in the cultivation of silk. He endeavoured to regulate the temperature, to introduce more order into the distribution of the food to the worms, to have more spacious premises, and to have these properly ventilated.
Now we are on this subject, we must mention the names of those who at the present day have rendered important services to sericulture—such as M. Camille Beauvais, who raised silkworm rearing from the inactivity into which it had been plunged; M. Eugène Robert, who founded in the south of France the first successful silkworm nursery; M. Guérin-Méneville, who has devoted his life to the study of the same question, and to whom Europe owes the introduction and the acclimatisation of some species which will render us, perhaps, one day very great services; and lastly, M. Robinet, who has elucidated several practical questions in the art of sericulture. In bringing to a close this rapid historical epitome, we will state that France consumes annually 30,000 kilogrammes of silkworms’ eggs, each kilogramme being at the present time worth from 300 to 500 francs, and even more. The value of manufactured silks represents annually about 8,000,000 francs; and we find by official statistics that France exported in 1863 silk stuffs to the value of 384,000,000 francs. This immense trade shows how much silk is now-a-days everywhere appreciated; in those numerous tissues called taffeta, satin, and velvet, each of which seems to have a charm—a peculiar attraction. The consistency of the stuff, the smoothness, the softness of surface, the manner in which silk receives colours, the brightness, fineness, power of reflecting, the rustling, the light or heavy folds,—all these are beauty, elegance, and luxury, in whatever way these words are understood.
The Bombyx mori has, however, nothing alluring in its appearance. Other caterpillars of the genus Bombyx have brilliant liveries; they are adorned with spots, blue as sapphires, green as emeralds, red as rubies, but produce threads without brightness and fineness. The humble silkworm, in a white blouse, like a workman, has nothing brilliant in its dress, and yet it gives to the whole world its most beautiful and gorgeous array. The body of the silkworm is composed of thirteen distinct segments. In front are three pairs of articulated legs, which will become later those of the moth. In the middle and towards the posterior part, are five pairs of membranous legs, furnished with a circle of very fine bristles, which assist the animal to hook itself on to leaves and stalks. On the two sides of its body are eighteen stigmata, or respiratory mouths.
The head of the silkworm is remarkable; it is scaly, horny, and formed of one single piece. The mouth is provided with six small articulated pieces. Below is a simple blade, the upper lip, having in its middle a hollow, into which the animal causes the edge of the leaf it is gnawing to enter, and holds it thus without any exertion. Underneath the lip are inserted two large jaws, which cut the leaf as a pair of scissors. Underneath, some weaker jaws divide the fragments, and a little organ, articulated on to each jaw, that is to say, a palpus, pushes them back towards the mouth, and prevents the smallest particle of the leaf from falling. And lastly, in the space comprised between the two jaws, is an under-lip, which completely closes the mouth below. At the extremity of this piece may be seen a little prolongation, a sort of papilla, pierced with a hole, which is the orifice that gives issue to the silky thread.
The organs which serve for the elaboration and emission of the silk have a peculiar interest for us. If we dissect a silkworm under water, we succeed, sooner or later, after having removed the outer parts, in laying bare a double apparatus, placed along the two sides of the intestinal canal and below it. This is the apparatus which secretes the silk; it is the double silk-bearing gland. Each one of these glands is composed of a tube formed of three distinct parts (Fig. 201). The part which is nearest to the tail of the worm is a bent tube, A B C, of a thirtieth of an inch in diameter, and about nine inches in length, twisted a great many times into irregular zig-zags. This part of the silk-producing organ is continued in an enlarged portion, D E, which is the reservoir of the silky matter. To the extremity, E, of this reservoir, is attached another capillary tube, E F. These two capillary tubes, proceeding from the two glands, unite together like two venous trunks, as the plate shows, in one single, short canal, F, which opens in the mouth of the worm, at its under-lip.
It is in the narrow hinder tubes that the silky matter is formed. It collects in the swollen part, D E, which is, properly speaking, the reservoir; and remains there in the glutinous state. Having reached the capillary tubes, it begins to assume consistency, and forms two threads, which are united together at the point of junction of the tubes, and come out through the orifice, with the appearance of a single thread, to be conducted and directed by the animal to those points it has selected.
It was hoped that by taking from the body of the worm the viscous matter contained in the glands, silk could be formed. But this hope was disappointed. It was found possible, it is true, to take the silk out; to draw it out into threads more or less fine; but up to this time it has only been possible in this way to obtain a matter which, when dried, more or less resembles catgut, and is easily enough spoilt by water.
The viscous substance contained in the glands must then be elaborated by the insect itself. When it arrives in the conduit common to the capillary tubes, under the form of a thread, it is impregnated with a sort of varnish, which is poured into them from two neighbouring glands. The varnish unites the two threads into one single thread, and imparts to it the brilliancy of silk, and the property of resisting the action of water. It is during the last phases of the worm’s development that the silky matter becomes abundant in the glands. At this period the animal eats much; and it is certain that the substance to be converted is furnished by the leaf of the tree on which the insect feeds.
In consequence of this having been remarked, some manufacturers have attempted to obtain their silk directly from the mulberry leaf; but they only get a bad floss or refuse silk. This is because the silk is not formed in the mulberry leaf. The organs of insects are laboratories, in which manipulations unknown to man are carried on, manipulations which he has not been able to imitate.
After this rapid glance at the fundamental parts of the organism of the silkworm, we will occupy ourselves with the natural history, properly so called, of this insect, and with its rearing, carried on with a view to the production of silk.
As belonging to the first part of this programme, we have to speak of the moult, of the ages of the silkworm, of its maturity, of its mounting or ascending season, of the formation of the cocoon, of the chrysalis, of the moth, and the eggs.
The name moult has been given to a sort of crisis during which the renewing of the skin of larvæ takes place. When it approaches, the silkworm changes its colour. Its robe, which was white or grey, and opaque, becomes yellow and somewhat transparent. The head swells considerably, especially above, and the skin becomes wrinkled (Fig. 202). The worm then fasts, and prepares to cast its skin. It places here and there some silk threads on the surrounding objects. It then slips under these threads, so that during its movements the old skin which it will abandon is, so to speak, gathered up. It then assumes a peculiar position, that represented in Fig. 203, and remains in it in a state of immobility which has been called sleep (sommeil).
During this sleep the new skin is formed under the old. A liquid oozes forth between the two membranes which separates them, and allows the silkworm to leave its old skin. To effect this, the worm begins by raising its head, and by making contortions. The old skin splits round the muzzle, or snout, on the head and back; then by different movements the animal emerges from its skin, which remains held up by the silken threads. The duration of the time occupied in moulting varies with the degree of the heat or humidity of the atmosphere; but in general the state of sleep lasts from twelve to twenty-four hours. One hour after the crisis the worm begins again to eat.
The ages of the silkworm are the periods of time which elapse between one moult and another. If we observe some silkworms when the temperature is favourable, we shall find that there are four moults, and consequently five ages. At the first age (Fig. 204), the silkworm is black and hairy; then of a nut colour at the moment when the first moult is going to take place. “The appearance presented by these worms collected together on a leaf,” says Dandolo, “is that of a downy surface of a dark chestnut colour, in the midst of which one sees nothing but a movement of little animals having their heads raised, working them about, and presenting black, shiny muzzles. Their bodies are completely covered with hairs arranged in straight lines, between which one perceives along the whole length of the body other longer hairs.” 60
The first age lasts for five days. At the second (Fig. 205), the worm is grey, almost without down, then of a yellowish white, and one sees the crescents making their appearance on the second and fifth segment. At the third age (Fig. 206), there is not a single hair remaining, and the worm becomes whitish, and is always becoming lighter. The third age lasts six days, as does also the fourth (Fig. 207). At the fifth (Fig. 208), the worm has very nearly reached the end of its career in the caterpillar state, and now is the time of its greatest voracity. This age is the longest; it lasts nine days.
At each of these periods in the life of the silkworm may be remarked a physiological fact to which has been given the name of frèze. When the silkworm has just moulted it eats little, but the time very soon arrives when it does so with extraordinary avidity. It is indeed insatiable. The frèze of the last age is called the grande frèze. It takes place about the seventh day. During this day worms, the produce of thirty grammes 61 of eggs, consume in weight as much as four horses, and the noise which their little jaws make resembles that of a very heavy shower of rain. It is at the end of this stage that the insect prepares the shelter in which is to be brought about its metamorphosis into a chrysalis.
A little while before this it ceases to eat, turns yellow, and becomes as transparent as a grape. It is now said to have reached its maturity. Up to this moment the worm had never tried to leave its litter. It lived a sedentary life, and never thought of wandering away from its food. Now it is seized with an imperious desire for changing its quarters. It gets up, it roams about, and moves its head in all directions to find some place to cling on to. It walks over everything within its reach, particularly over those obstacles which are placed vertically. It aspires, not to descend, like the heroes of classic tragedy, but to rise. It is for this reason that this period of the silkworm’s life has received the name of the mounting or ascending season. It now looks for a convenient place in which to establish its cocoon. Every one has remarked how the animal sets to work to accomplish its task. It begins by throwing from different sides threads destined for fixing the cocoon; this is what we call refuse silk. The proper space having been circumscribed by this means, the worm begins to unwind its thread—a continuous thread of about a thousand mètres long.
It has been calculated, let us say by the way, that forty thousand cocoons would suffice to surround the earth at the equator with one thread of silk. Folded on itself almost like a horse-shoe, its back within, its legs without, the worm arranges its thread all round its body, describing ovals with its head. It approximates gradually the points of attachment of the thread. As long as the cocoon is not very thick one can watch it through the meshes of the web applying and fixing its thread, still to a certain degree soft, in such a manner as to make it adhere closely to the parts already formed.
“We can state,” says M. Robinet, “that the silkworm makes every second a movement extending over about five millimètres. The length of the threads being known, it follows that the worm moves its head three hundred thousand times in making its cocoon. If it employs seventy-two hours at its work, it is a hundred thousand movements every twenty-four hours, four thousand one hundred and sixty-six an hour, and sixty-nine a minute, that is to say, a little more than one a second.”
About the fourth day, after having expended all its silk, 62 the worm shut up in the cocoon becomes of a waxy white colour, and swollen in the middle of its body. The abdominal legs wither away; the six fore legs approach each other and become black. The parts of the mouth tend downwards; the skin wrinkles. Very soon it is detached and pushed down towards the hinder part, and the chrysalis appears under the rents in the skin. It is at first white, but speedily becomes of a brown red.
The silkworm remains in general from fifteen to seventeen days in the pupa state. At the moment of hatching, the moth begins by breaking the skin in which it is shut up, and which is pretty thin. But how can it come out of the silky prison which it has itself built? To effect this it makes use of a peculiar liquid contained in a little bladder with which its head is provided, and which was discovered by M. Guérin-Méneville. It moistens the cocoon with this liquid; which soaks through and penetrates the whole thickness of the silken wall which confines it. The threads of silk of which it is composed are moistened and disunited, but not broken. The moth opens a passage for itself through the threads thus separated, and makes its appearance in the light of day. Its wings are folded back on themselves, and it is still quite wet, but it seeks immediately for a good place in which to dry itself, and in a little time assumes its final appearance (Figs. 209, 210). The female (Fig. 210) has whitish wings, the antennæ only slightly developed and pale, the abdomen voluminous, cylindrical, and well filled. It is quiet, heavy, and stationary. The male is smaller; its wings are tinged with grey, its antennæ blackish; it moves about, beats its wings together, and is lively and petulant.
Before laying her eggs, the female looks out for a place suitable for this purpose. When she has found this place, she ejects an egg covered with a viscous liquid, which causes it to adhere to the body upon which it falls. Very soon she lays a second egg by the side of the first, then a third by the side of the second, and so on. She very rarely piles them up on each other. The laying lasts about three days; the number of eggs is from 300 to 700 for each female. These eggs are generally tentacular and flattened towards the centre. At the moment at which they are laid they are of a bright yellow. In a week they become brown. The colour changes then to a reddish grey; lastly it becomes of a slaty grey, remaining this colour during the autumn, winter, and a great part of the spring. Then as the temperature rises, the colour of the eggs passes successively through bluish, violet, ashy, and yellowish shades. And, lastly, they become more and more whitish every day as the hatching time approaches.
If looked at closely, one remarks a black spot and a brownish crescent extending along the circumference. The black spot is the head of the worm, which closely touches the shell; the crescent is the body, which is already covered with little hairs. When it leaves the egg, the silkworm gnaws through the shell on its side, never on its flat surface. When the opening is large enough, it breaks out through it, head foremost, and immediately fixes a thread of silk to any object it can reach, no doubt in order to prevent itself from falling. Sometimes the opening is too small to allow of the head passing out, and the larva is forced to come out backwards, that is to say, tail foremost. At times, not being able to get its head free, the poor animal very soon dies of fatigue and hunger.
We will now give a summary of the rearing of the silkworm, that is to say, of the attention which must be paid to this insect that it may construct its cocoon advantageously. We will call to our aid in this very rapid summary the works or notices of MM. Robinet, Guérin-Méneville, Eugène Robert, and Louis Leclerc, and we must not forget the excellent and classical Dandolo. 63
When it is desired to rear silkworms—magnans, as they were called in old French, and as they are still called in the patois of Languedoc—the first thing to do is to obtain good eggs, good grain, to use the technical word, and then to choose suitable premises. The essential, the fundamental point, in the rearing, is to possess premises in which the air is easily renewed. The worms should have as much air as possible given to them without ever being allowed to be chilled. There is no better means of attaining this end than by keeping a constant open fire in a room, and by letting air into the room from another chamber which separates it from the open air. One has, in this way, the best workroom for a small rearing.
In the workshop are arranged racks, by the aid of which are placed, at the distance of 50 centimètres from each other, frames made of reeds. These frames, or canisses, as they are called in the Cévennes, may be from 1 mètre to 1¾ mètres in breadth. They should be placed in such a manner that one can easily pass round them to place and remove the worms, and to distribute their leaves to them uniformly. They should be protected by a small border of a few centimètres in height, to prevent the worms from falling. And lastly, they should be covered at the bottom with large sheets of paper. (Plate VI.) A provident silkworm-rearer has always at his disposal a cellar or cool room, so as to be able to stow away his leaves as soon as they are brought in from the country.
What we have just said applies especially to a small rearing. In large establishments, or even those of second-rate importance, everything is in advance of this, and mathematically regulated: aspect and arrangement of rooms, furniture of these rooms, warming, ventilation, &c. So, for a rearing house for 300 grammes of eggs, the building should be constructed in such a manner that its front and back look east and west, to avoid any inequality in the heat derived from the sun. It ought to consist of a ground-floor, a very lofty first-floor, and of a rather low roof. The ground-floor comprises the chamber of incubation, the store-room for leaves, and the air-chamber with the grate intended for warmth and ventilation. The first-floor constitutes the rearing-room properly so called.
But let us leave these grand industrial establishments, to return to our rearing houses on a small scale, such as are found among the peasants of the Cévennes. They generally receive the silkworms’ eggs before the end of the winter. In order to preserve them till the hatching season, they are placed in thin layers, in a piece of folded woollen stuff, which must be hung up in a cool, but not a damp place, exposed to the north. As soon as the buds of the mulberry tree begin to be partially open, they proceed to the incubation of the eggs. They are spread out on sheets of paper, in very thin layers, placed on a table in a room having a southern aspect, and left thus during three or four days, taking care to prevent the rays of the sun from touching them. It is necessary also, from time to time, to open the windows. After three or four days, the fire is lighted, taking care not to have more heat than 13° Centigrade round about the table which supports the eggs, and which should be placed as far as possible from the fire. Each day the room is warmed a little more, in such a way that the temperature is raised 1° to 2° a day, until 25° Centigrade of heat have been attained, at which temperature it is to be maintained when the eggs have reached the last stage, and till the hatching is terminated. On the first day few worms are hatched; but the hatching of the second day is very abundant, as also that of the third. Of these newly-born worms two divisions are made, separated by an interval of twenty-four hours. The worms which are born afterwards are thrown away, unless they are so abundant that they can be made a third batch of, which is to be mixed up with the second at the period of the moult.
In the large rearing houses there is a special chamber for the incubation. Various simple, convenient, cheap apparatuses, whose main object is to create a permanent warm and damp atmosphere, whose degree of heat can be regulated at will, have been proposed. M. Louis Leclerc, in his pamphlet entitled “Petite Magnanerie,” has given a description and drawing of a little box which is very useful for facilitating the hatching of eggs. We refer those of our readers who wish for further information on the subject to that work. As soon as the worms are hatched, the eggs are covered with net, and over this are placed mulberry boughs, covered with tender leaves, on which all the little worms congregate. They are then lifted up with a hook made of thin wire, and the worms are placed on a table covered with paper, leaving a proper space between each. They are given, as their first meal, tender leaves cut into little pieces with a knife. These are the operations gone through for the two raisings of worms on the second and third day of the hatching. During this first age they give them from six to eight meals a day, taking care to distribute their food to them as equally as possible. The first meal is given at five o’clock in the morning; the last at eleven or twelve o’clock at night.
When the moult is approaching, the young ones are made to climb on to boughs having tender leaves, so that they can be moved to litters as thin and clean as possible, and there sleep in a good state of health. When the mass of worms is well awake again, the next thing to do is to take them off the litter on which they moulted, and to give them food. If this problem were proposed to a person strange to the operation which is now occupying our attention—to separate the worms from the faded and withered food upon which they are reposing, without touching them—he would certainly be very much at a loss what to answer. The solution of this problem presented for a long time great difficulties, and occasioned numerous reverses in the rearing. Now-a-days, thanks to the employment of a net, the délitement, or taking them off their bed, has become an easy operation.
Over the worms, placed on a table, is spread a net, the meshes of which are broad enough to allow them to pass through. On this net are spread the leaves which are to compose a meal. The worms immediately leave the old food, and get on to the new leaves. They then lift the litter with the worms, and throw away the old leaves, now unoccupied, clean the table, and replace the net with the worms. At the next délitement the first net is found under the litter. Figs. 211 and 212 represent two forms of these nets made of thread.
Thread nets, which were of great use, have been supplanted lately, with great advantage, by paper ones, which were invented by M. Eugène Robert. These are leaves of paper, of a peculiar manufacture, pierced with holes proportioned to the size of the worms which are to pass through them. The paper net can be used advantageously also for separating the worms that are too near together, or, as they say, for the dédoublement. Formerly, the délitement and the dédoublement were done by hand—a tedious work, and one that presented serious disadvantages. Now-a-days, as we have seen, the worms themselves perform these two perilous operations.
At the second age they still cut the leaves for the worms, but into larger pieces, and proportioned to their size. During the day the temperature of the room ought to be kept to 21° Centigrade, but it may be lowered by 1° or 2° during the night. Towards the end of this age they have only four meals. When the worms are on the point of going to sleep, their meals are decreased.
During the third age the number of the meals is kept to four, the first being given towards five o’clock in the morning, and the last between ten and eleven o’clock at night. The leaf is cut into much larger pieces, and distributed as equally as possible. The délitement and the dédoublement are proceeded with as in the preceding age. One begins to find pretty often during this period of the life of worms, some luisettes—that is to say, worms which have not strength enough to moult. They are larger than those just woke up, and that have not as yet eaten, and are shiny. They must be carefully removed, for they will not be long before they die, and infect the air of the room.
During the fourth age they no longer cut the leaves, but give them a great deal more at once. The result is that the litters increase in thickness, and that the délitement must be performed oftener; for the rest, four meals are always necessary. Many luisettes may be seen during the fourth age. The moult which follows the fourth age is the most critical phase in the life of the silkworm. During their sleep they are a prey to acute suffering, and are plunged into a state of lethargy which resembles death. The dryest and cleanest litters diffuse very soon a sickly smell. This moult lasts from thirty-six to forty-eight hours. During this time the room should be kept to at least 22° Centigrade.
When they awake out of this last sleep the attendant should continually be on his guard, as it is then that diseases break out. The worms suffering from these different diseases have received different names. There are besides the luisettes the arpians—that is to say, worms that have exhausted all their energy in the work of the last moult, and have not even strength to eat—the yellow, or fat worms, which are swollen, of a yellowish colour, and which very easily die; the flats or mous, the soft or indolent ones which, after having eaten a great deal and become very fat, die miserably, and enter into a state of putrefaction. And lastly, it is at this age that the muscardine, which hardly shows itself at any other age of the insect, appears with great intensity.
The muscardine is a terrible scourge to the rearers of silkworms. The losses which result from this disease in France are estimated at at least one-sixth of the profits. No particular symptom allows of our recognising the existence of this disease in worms which, however, contain its germ; only, the worm, which has eaten up to that time as usual, appears almost in a moment to change to a duller white; its movements become slower, it becomes soft, and is not long before it dies. Seven or eight days after its death it becomes reddish and completely rigid. Twenty four hours afterwards a white efflorescence shows itself round the head and rings, and soon after the whole body becomes floury. This flour is a fungus called Botrytis bassiana, of which the mycelium develops itself in the fatty tissue of the caterpillar, attacks the intestines, and fructifies on the exterior. This fungus has been considered as the immediate cause of the muscardine, and has been also regarded as the last symptom or end of the disease. The communication of the disease by contagion has alternately been admitted and denied. As its true cause, and any efficacious means of opposing it, are still unknown, the breeders of silkworms must be content to apply—so as to prevent or struggle against this dreadful scourge—the precepts of hygiene: good ventilation, excessive cleanliness, frequent délitements, and good food properly prepared.
After the muscardine, we must mention another epidemic disease still more terrible, the gattine. This disease shows itself from the very beginning of the rearing, and increases in intensity at each age, so that the number of worms able to enter regularly into the moult becomes smaller and smaller. We are still in a state of utter ignorance as to the cause of this last affection, which has occasioned, for the last ten years, incalculable losses in the rearing houses, which threatens the silkworm with complete destruction, and which in the meanwhile has ruined the unfortunate countries of the Cévennes, the principal seat of sericulture in France.
During the fifth age, the worms become large so quickly that on the fifth or sixth day they are obliged to be moved away from each other on the litter. The délitement must be made every two days, or indeed, every day now, on account of the enormous amount of the excrement; and, at the same time, a good ventilation must be constantly maintained. The temperature of the room should now be kept to 24°, without ever exceeding this degree of heat. When it is perceived that the worms wish to ascend, or mount, there are placed on the tables, at certain distances from each other, little sprigs of heather or very dry branches of light wood.
When the worms begin to mount into the heather, one must encabaner—that is to say, form with these branches little hedges, curved back like a hut or cradle, the openings of which are, on an average, seventeen inches or so (Fig. 213). At the expiration of twenty-four hours all the good worms have mounted. The laggards who remain under the cabanes are taken off by hand, and placed on a table, which is immediately encabanea.
The cocoons spun on these branches of heather ought to be large, heavy, and well-shaped. The good cocoons are regular; their ends are rounded and not pierced; and they are hard, especially at their extremities, and have a fine grain. They are cylindrical. The best are drawn in towards the middle, or have a concavity on either side of it (Fig. 215). Every one knows that there are white and yellow cocoons. They are the produce of different races of worms.
Commerce recognises two kinds of white silk: the first white and the second white. The silk of the first white is produced by the race Sina, the cocoons of which are of a perfect and azured white. They produce the most beautiful and most precious silk, and serve for the fabrication of light and delicate coloured tissues. The silk of the second white is furnished by two races: the Espagnolet and the Roquemaure.
The races that produce yellow cocoons are more numerous than the white ones. The yellow races are divided into three groups: those that have small, middle-sized, or large cocoons. The first and second are stronger, and more esteemed than the last.
The greater number of the races of silkworms have, let us here mention, white and yellow cocoons; there are some, however, whose cocoons are of a greenish white, or even quite green, or of a reddish green. One race, raised in Tuscany, near Pistoia, has cocoons of a pale rose colour; and, lastly, mention has been made of cocoons of a purple colour.
When the cocoons are completed, the people in charge of the rearing establishments separate them from the heather and sell them to the silk-spinners. But they must manage to get these cocoons into a state in which they will remain entire during a long time. They must, in other words, kill the chrysalis, to prevent the cocoons being pierced by the moth. To kill the chrysalis so as to prevent the development of the imago is an operation which is called the étouffage, or stifling.
To effect this stifling, the cocoons are exposed to a high temperature. Formerly, in the Cévennes, the cocoons were placed in a baker’s oven, heated for baking bread. But they ran the risk thus of being burnt, or of a certain number of chrysalides remaining alive. Now, to kill the chrysalides, they make use of steam at 100°, produced by water boiling in a vessel, and which passes through wicker baskets filled with cocoons.
The rearer must also take care at the time he gathers them, to separate the cocoons which are to provide eggs for the next year. As the female cocoons are heavier than the male cocoons, they are easily separated by weighing them in a pair of scales.
To obtain the eggs, or grain, the cocoons are fixed on sheets of brown paper, covered with a slight coating of paste made of flour. They are arranged in such a manner that the moths shall find no obstacle when they come out of them, head foremost; and, moreover, so that they may be able to reach with their legs the cocoon which is opposite them, so as to hang on to it, and to facilitate their exit from their own cocoon (Fig. 218). The male and female cocoons are pasted on separate sheets.
It is from fifteen to twenty days after the montée, or mounting, and when the temperature of the rooms has been kept between 20° and 25°, that the moths begin to be hatched. As they appear, they are seized by the wings and placed on cloths stretched out for the purpose, where they are left for about an hour, till their wings have fallen flat on their bodies. As soon as they have evacuated a red liquor, the males and females, which up to that time have been apart, are put together.
They then stick sheets of paper on to screens, putting from twenty-five to thirty females on each sheet (Fig. 219). It is here the moths lay their eggs. The sheets of paper, covered with eggs, are then hung on wires, at a small distance from the ceiling of a room having a northern aspect, which is never warmed. They remain thus, exposed to all variations of temperature, till the return of the warm weather. We will say a few words, to bring this subject to an end, on the winding of cocoons and the spinning of silk.
The winding of cocoons is an operation which at first sight appears very simple, but which is in reality a difficult and delicate process. It requires unremitting attention, great experience, and a delicacy of touch which can only be found in the fingers of woman, or rather, in the fingers of certain women.
The woman who is spinning, stands before a sort of loom which is called tour (Fig. 220). Under her hand is a copper containing water, which she heats to the required degree by opening the tap of a tube, which brings a current of steam. She plunges the cocoons into the hot water, and moves them about in it, to soften the gummy substance which sticks the silken threads of the cocoon together. Then she beats them, with a light hand, with a small birch-broom. The threads of the cocoons get caught in the extremities of the twigs of which the little broom is made, and the workwoman seizes with her fingers the bundle of threads, and shakes them about till she perceives that they are all single, and in a fit state to be joined together.
Let us suppose that it is wished now to make up a brin, or staple, by uniting together the ends of five cocoons. She chooses five ends in the mass, makes of these a bundle, and introduces it into the hole of a filière. She makes two staples (brins) at once, one on her right, the other on her left hand. She then brings them together, she crosses them, rolls them, and twists them, the one on the other, several times; after which, she separates them from above and keeps them well apart, making each of them pass into a hook at a distance, from which they are going to twist round into a hank, separately, on a wheel. The two threads thus twisted are drawn close together, compressed, and become one, getting round by rolling on each other, and being kept in continual motion, drawn out as they are by the rapid motion of the wheel.
The difficulty which the emptying the cocoon of its silk thread presents, makes us understand what difficulties those manufacturers must have met with who have lately attempted to extract from the stalks of mulberry leaves a sort of silk. We will enter into no details of the attempts which have been made to accomplish this object in our time, attempts which have, however, been crowned with no success whatever. We will confine ourselves to reminding the reader that these attempts are far from being of recent origination, since they date back to as far as Olivier de Serres, the father of French sericulture.
In a little work published by Olivier de Serres, in 1603, under the title of Cueillette de la Soie, “The Gathering of Silk,” we find a memoir entitled: La second richesse du mûrier, qui se trouve en son escorce, pour en faire des toiles de toute sorte, non moins utile que la soie provenant d’icelui, “The second wealth of the mulberry tree which is found in its bark, how to make of it cloth of all sorts, not less useful than the silk derived from this tree.” Olivier de Serres proves in this memoir that the second bark, or liber, of the mulberry tree contains a fibre capable of replacing hemp or flax, and he describes the processes by which this may be obtained. The processes which had been proposed by Olivier de Serres in 1603, were resumed in the Cévennes a dozen years ago by M. Duponchel on the one hand, and on the other by M. Cabanis, 64 who operated on the bark instead of taking the whole of the wood of the mulberry tree. But none of these attempts have given any good results up to the present moment.
The various diseases which for the last fifteen years have been so fatal to the mulberry silkworm, have suggested the idea of acclimatis ing in Europe other silk-producing Bombyces, if not with the view of superseding, at least as auxiliaries to the mulberry species. The genus Attacus has furnished these auxiliaries. Among the species which have, in this respect, the greatest claims to our attention, we must place in the first rank those which feed upon the leaves of the oak tree. Indeed, the trees which can be made use of for their cultivation are very numerous in Europe, and, moreover, the silk produced by these worms appears to possess superior qualities.
There are three oak-feeding species of the genus Attacus. They are Yama-Maï, Pernyi, and Mylitta.
The silk of Yama-Maï is as bright as that of the mulberry silkworm, but a little less fine and strong, and occupies the first rank after it. If we could succeed in acclimatising this species it would supply any deficiency there might be in our crops of ordinary silk.
The eggs of the Attacus Yama-Maï were brought from Japan—where this worm is reared—conjointly with the mulberry silkworm, in 1862. The larvæ hatched at Paris, in 1863, were green, of a great size, remained in that state eighty-two days, and were easily reared. Their cocoon resembles that of the mulberry species. It is composed of a beautiful silk of a silvery whiteness in the interior, and of a more or less bright green on the exterior. The moth is very large and beautiful, of a bright yellow colour, approaching orange.
We give a drawing of the Attacus Yama-Maï, taken from the plates which accompany M. Guérin-Méneville’s memoir. 65
Fig. 221 represents the larva, or caterpillar, two-thirds natural size; Fig. 222, the cocoon, drawn on the same scale; and Fig. 223, the moth.
In 1866, M. Camille Personnat published a very interesting monograph of Yama-Maï, which may be consulted with profit by both cultivators of silk and naturalists. 66
Attacus pernyi yields a remarkably beautiful silk, fine, strong, and brilliant, which can be spun and dyed with great ease. The tissues obtained from it partake of the qualities of ordinary silk, of wool, and of cotton. This species of Attacus, which is reared on the oak in Mandchouria, has given rise to great hopes in France. The cocoons and moths of this worm were exhibited for the first time at the Universal Exhibition of 1855. They were reared by M. Jordan, of Lyons, from some cocoons sent over from China by the missionaries. It is much to be desired that this species may be acclimatised in Europe.
Figs. 224 and 225 represent, after drawings in the Memoir of M. Guérin-Méneville, already referred to, the cocoon and moth of the Attacus pernyi.
The silk which Attacus Mylitta produces is perhaps superior to that of Pernyi. When the cocoons are properly prepared, the silk can with ease be wound off from one end of them to the other. This worm is found in various parts of Bengal and of Calcutta, and also at Lahore, and its silk is exported in considerable quantities under the name of tusseh. Brownish stuffs are made of it in India of firm and bright texture, which are used for summer clothing, or for covering furniture.
Figs. 226 and 227 represent the moth and the cocoon of Attacus Mylitta after M. Guérin-Méneville.
In 1855 M. de Chavannes reared this species in the open air, near Lausanne, in Switzerland. This treatment succeeded perfectly, without any degeneration, for many years. It, however, died out at last, from the effects, perhaps, of too great a difference in the climate, or from those accidents, still so little understood, to which even the insects of our own country are subject. This was unfortunate, as this species is one of those whose acclimatisation in Europe is the most to be desired, for it would render great service to the cultivators of silk.
It remains for us to speak of two other species, which are very important, inasmuch as their domestication in Europe is now an accomplished fact. We mean the Attacus or Bombyx of the Ailanthus, and also that of the Castor-oil plant.
Every one has heard of the Ailanthus silkworm (Attacus [Bombyx] Cynthia), whose acclimatisation in Europe has been materially assisted by the admirable and persevering efforts of M. Guérin-Méneville.
The Ailanthus worm is a native of Japan and of the north of China. It was brought over in 1858 by Annibale Fantoni, and sent to M. Guérin-Méneville by MM. Griseri and Colomba, of Turin. When it is nearly full-grown it is emerald green, with the head, the feet, and the last segment of a beautiful golden yellow, and has black spots on each segment. This worm, in its full-grown state, is represented by Fig. 228; in the same figure are also represented the eggs and the cocoon. The moth has the abdomen yellowish underneath, with little white tufts. Its wings are traversed by a white band, which is followed exteriorly by a line of a bright rose; each wing is also marked by a lunula or crescent-shaped spot.
In 1858 M. Guérin-Méneville presented to the Académie des Sciences of Paris the first moths and the first eggs laid in France of the Attacus Cynthia. This able entomologist demonstrated very soon afterwards—1st, that the caterpillars of this insect can be reared in the open air, and with scarcely any cost for management; 2ndly, that it produces two crops a year in the climate of Paris and the north of France; 3rdly, that the cultivation of the Ailanthus, or the false Japan varnish tree, on which this insect lives, is easy even in the most sterile soil.
M. Guérin-Méneville showed still further that ailantine, the textile matter furnished by the cocoon of the Cynthia, is a sort of floss silk holding a middle place between wool and the silk of the mulberry-tree worm, and which, as it can be produced at scarcely any expense, would be very cheap, and would serve for the fabrication of what are called fancy stuffs, for which ordinary floss silk is now used. In 1862 M. Guérin-Méneville sent in a Report to the Minister of Agriculture on the progress of the cultivation of the Ailanthus, and of the breeding of the silkworm, which was reared in the open air on this tree. He mentions, in his Report, the rapid development of the cultivation of the tree in France, the great number of eggs of the Ailanthus silkworm sold, the foundation of a model silkworm nursery at Vincennes, and, this one great point gained, that they had found out the way of unwinding the silk from the cocoons of the Cynthia in one unbroken and continuous thread.
Till then European industry had only succeeded in drawing from the cocoons of the Ailanthus silkworm a floss silk, composed of filaments more or less short, obtained by carding, and unable to produce, when twisted, anything better than floss, that is to say, refuse silk. It is to the Countess de Vernéde de Corneillan, on the one hand, and to Doctor Forgemot on the other, that the merit is due of having obtained an unbroken thread of silk from the cocoon of Attacus Cynthia.
A monograph on the Ailanthus silkworm appeared in 1866 under the title, “L’Ailante et son Bombyx, par Henri Givelet.” 67 It is a complete account of all the results obtained up to the time, both as regards the rearing of the silkworm and also as regards the cultivation on a large scale of the Ailanthus, or false Japan varnish tree. 68
The Castor-oil Plant Silkworm (Attacus [Bombyx] ricini) is a species very nearly akin to the Ailanthus worm, perhaps only a variety, and comes from India. The silk which it produces is very similar in every respect to that of the Cynthia. The rearing of this worm could never attain to any great importance in France, on account of the necessity there is of renewing the plantations of the castor-oil plant each year. It would, however, afford an additional source of income to the farmers in the south of France, who cultivate the castor-oil plant with a view to selling its seeds, which are much used in pharmacy.
Nearly allied to the genus Attacus, which furnishes us with all these precious auxiliaries to the mulberry silkworm, are a great number of other species, both indigenous to Europe and exotic, mostly remarkable for their great size, and a few of which are common in this country.
Fig. 229 is the largest European moth, but never found farther north than the latitude of Paris. Its wings are brown, waved, and variegated with grey. Each of them has a large black eye-shaped spot, surrounded by a tawny circle, surmounted by one white semicircle, and by another of a reddish hue, the whole completely enclosed in a black circle. “These moths,” says Geoffroy, “are very large; they look as if they were covered with fur, and, when they fly, one is inclined to take them for birds.”
Saturnia pavonia-major comes from a very large caterpillar, which is of a beautiful green, with tubercles of turquoise blue, each of which is surmounted by seven stiff divergent hairs. This caterpillar lives principally upon the elm, but it feeds also upon the leaves of the pear, plum, and other trees. It spins a brown cocoon, formed of a coarse silk of great strength. It is not until the following spring that it becomes a moth.
The Emperor Moth (Saturnia carpini, Fig. 230) much resembles the above, except in size. This species is common in England, and its green larva, covered with black or pink warts, from which spring hairs, as in the last, is by no means rare on heath in the autumn. It also feeds on bramble and other plants.
Among the Attaci foreign to Europe, we must mention Atlas (Fig. 231), the expanse of whose wings exceeds four and a quarter inches. This magnificent moth, one of the largest known, comes from China.
The family Bombycidæ comprises many species which we must not omit to mention.
The Lackey (Bombyx neustria) derives its name from the colour of the caterpillar, which has longitudinal lines of various colours, and a blue head. These caterpillars live together on a great number of our forest and garden trees, to which they do much damage. The moth (Fig. 232) has a brownish body, and wings of a more or less tawny yellow colour, with two darker lines on the front wings.
The Procession Moth (Bombyx processionea) is a small greyish moth, the caterpillars of which live in numerous troops on oak trees, and devour the leaves at the moment of their development. In the evening these caterpillars come out of their common nest, and form a sort of procession; hence their name Procession Moth. “I kept some for a little time in my house in the country,” says Réaumur. “I brought an oak branch which was covered with them into my study, where I could much better follow the order and regularity of their march than I could have done in the woods. I was very much amused and pleased at watching them for many days. I hung the branch on which I had brought them against one of my window shutters. When the leaves were dried up, when they had become too hard for the jaws of the caterpillars, they tried to go and seek better food elsewhere. One set himself in motion, a second followed at his tail, a third followed this one, and so on. They began to defile and march up the shutter, but being so near to each other that the head of the second touched the tail of the first. The single file was throughout continuous; it formed a perfect string of caterpillars of about two feet in length, after which the line was doubled. There two caterpillars marched abreast, but as near the one which preceded them as those who were marching in single file were to each other. After a few rows of our processionists who were two abreast, came the rows of three abreast; after a few of these came those which were four abreast; then there were those of five, others of six, others of seven, others of eight caterpillars. This troop, so well marshalled, was led by the first. Did it halt, all the others halted; did it again begin to march, all the others set themselves in motion, and followed with the greatest precision.... That which went on in my study goes on every day in the woods where these caterpillars live.... When it is near sunset you may see one caterpillar coming out of any of the nests, by the opening which is at the top, which would hardly afford space for two to come out abreast. As soon as it has emerged from the nest, it is followed by many others in single file; when it has got about two feet from the nest, it makes a pause, during which those who are still in the nest continue to come out; they fall into their ranks, the battalion is formed; at last the leader sets off marching again, and all the others follow him. That which goes on in this nest takes place in all the neighbouring nests; all are evacuated at the same time.”
One part of Fig. 233 shows the arrangement of the caterpillars on coming out of the nest. These caterpillars are furnished with long hairs, slightly tufted, which come off with the greatest ease, and which if they penetrate into the skin, cause violent itching. In 1865 a number of the alleys of the Bois de Boulogne were shut up from the public in order to save them from this annoyance. These caterpillars construct a covering common to them all, in which they live, and transform themselves therein, each insect making for his own private use a small cocoon. This insect is said to have been found in England, but there is not sufficient evidence to admit it into our lists.
The Orgyias comprise a great number of small species, of a dark colour, which do a great deal of damage to our forest trees. In Sep tember and October the male of the Orgyia antiqua, with his tawny wings, may often be seen flying about the streets of London. The female (Fig. 234) is remarkable, as she has only the rudiments of wings, and only goes as far as the side of her cocoon. The caterpillar of the Orgyia pudibunda, called also the Hop Dog, attacks almost every sort of tree. When the state of the atmosphere favours their propagation, they appear in fearful quantities, and cause the greatest havoc. During the autumn of 1828, in the environs of Phalsbourg, they were to be counted by millions. The extent of the woods laid waste was calculated at about fifteen hundred hectares. It is common in this country.
Among the genus Liparis, the species of which are also very destructive to trees, we must mention the Brown-tailed Moth (Liparis chrysorrhœa, Fig. 236), a species by no means rare in England. The caterpillars live in quantities, on apple, pear, and elm trees, and destroy the plantations of the promenades of Paris.
The females of this genus tear off the fur from the extremity of their abdomens to make a soft bed for their eggs, and to preserve them from the cold. And yet they are never to see their young, for they die after they have laid their eggs. Another tribe of Bombycina contains species of a small size, which are remarkable from the habits of their caterpillars, which make, with foreign bodies, cases, in the interior of which they live and undergo their metamorphoses.
The caterpillars of the genus Psyche live in a case composed of fragments of leaves, of bits of grass and straw, of small sticks of wood, or of little stones, stuck together, and intermixed with silky threads.
We give a representation (in Figs. 237, 239, and 240) of the cases of the caterpillars of three different kinds. The females of these moths are completely destitute of wings, and resemble caterpillars. As a general rule they hardly ever leave their case. The males (Figs. 238, 242) are of a blackish grey, and fly very swiftly.
The caterpillars of the genus Hepialus are difficult to observe, as they live in the interior of the roots of various vegetables. Such is the common Ghost Moth (Hepialus humuli), which sometimes causes the greatest damage.
The type of the genus Zeuzera is Zeuzera æsculi, or Wood Leopard (Fig. 243). It has white wings with large blackish blue spots on the anterior, and small black spots on the posterior wings. The caterpillar, of a vivid yellow, spotted with black, lives in the interior of the trunks of a great many trees, principally the chestnut, the elm, the lime, and the pear tree. This moth, which is known also by the name of Coquette, is to be seen in the evening flying about the public gardens of Paris, and is not rare in England. The most celebrated species of the allied genus Cossus is the Wood-boring Goat Moth (Cossus ligniperda), figured in the opposite plate. The moth has a heavy brownish body and greyish wings streaked with black. It is found in most parts of Europe. The caterpillar is of a reddish colour, as if it had on a leathern jerkin, and disgorges a liquid which is believed to soften ligneous fibres, and it lives in the interior of willows and other trees. It was on this caterpillar that Lyonnet made his admirable anatomical researches.
Another tribe of Bombycina comprises some very strange caterpillars, whose hindermost feet are changed into forked prolongations, which they move about in a threatening manner. These sort of fly-traps are perhaps meant to keep at a distance those insects which would lay their eggs upon the caterpillar’s body. The caterpillars of Dicranura are of this kind. We give a representation of the caterpillar and the moth of the Puss Moth (Dicranura vinula, Figs. 244, 245), as also the moth of the Dicranura verbasci, the former of which is common in England, and the larva may be found during the late summer and early autumn feeding on poplars and willows; and of the caterpillar of Stauropus fagi, the Lobster Moth (Fig. 247), rare in France, whose appearance is strange indeed. The moths, on the contrary, have nothing about them remarkable.
The Noctuina are a group of Lepidoptera of middling size, and generally found in woods, meadows, and gardens, where their caterpillars have lived. They seldom fly till about sunset, or during the night. Their upper wings are of a dark colour, with spots in the middle of a particular shape. Their lower wings are of various colours, often whitish, sometimes red or yellow.
We give representations of some of the species of this group. 69 Noctua tegamon, Fig. 248; Noctua nebulosa, Fig. 249; Noctua musiva, Fig. 250; Noctua brunnea, Fig. 251; Catocala fraxini, Fig. 252; Catocala Americana, Fig. 253; Catocala paranympha, Fig. 254; Catocala nupta, Fig. 255, the Red Underwing; and Erebus strix, Fig. 256.
The bodies of these moths are robust and sometimes massive, and are scaly rather than woolly. The thorax is sometimes bristling with hairy tufts.
This genus includes 800 species, of which there are about 300 in France. The caterpillars of the Noctuina are smooth or very slightly covered with hair, usually of a pale colour, and live on low plants, of which they devour, some the leaves, others the roots; then it is they are most destructive to agriculture. There are some of them which eat any caterpillars they may chance to meet, and even those of their own species, leaving nothing but the skin. Some of them surround themselves with a light cocoon before becoming chrysalides; others bury themselves in soft, well-pulverised soil.
The family of Geometrinæ, or Geometers, comprises moths of a middling size, and usually flying after sunset and during the night. 70 They frequent the alleys of damp woods, where they become the prey of the Libellulæ 71 and other carnivorous insects. Their bodies and abdomens are slender, their wings large, thin, fragile, often of a dark colour, with brilliant markings.
The caterpillars of the Geometrinæ are known by the name of loopers or geometers. We have previously described their singular organisation. They are continually spinning a silken thread, which keeps them attached to the plant on which they live. If you touch the leaf which supports them they immediately let themselves fall.
“Nevertheless, they do not generally fall to the ground,” says Réaumur; “there is a cord ready to support them in the air (Fig. 257), and a cord which they can lengthen as they will; this cord is only a very thin thread, but has nevertheless strength enough to support the caterpillar (Figs. 258, 259). All that there seems to fear is, that the thread may lengthen too quickly and the caterpillar fall, rather than descend gently, to the ground. But what we must first remark and admire is, that the caterpillar is mistress of its movements, and is not obliged to descend too quickly; it descends by stages; it stops in the air when it pleases. Generally it only descends at most about one foot at a time, and sometimes only half a foot or a few inches, after which it makes a pause more or less long, as it pleases.” It is in this way that the caterpillars let themselves fall from the top of the highest trees: they remount again with no less ease.
Let us listen to Réaumur’s description of the means employed by this caterpillar to ascend these heights. Figs. 260 and 261, drawn, as the three preceding ones, from the plates in Réaumur’s Memoir, help us to follow the explanation given by the illustrious naturalist of the evolutions of our little acrobat:—“To remount,” says Réaumur, “the caterpillar seizes the thread between its jaws, as high up as it can; as soon as it has done this it twists its head round, lays it over on one side, and continues to do so more and more every moment. Its head seems to descend below the last of the scaly legs which are on the same side as that to which it is inclined. The truth is, however, that it is not its head which descends, the part of the thread which it holds between its jaws is a fixed point for its head and for the rest of its body; it is that portion of the back corresponding with its scaly legs which the caterpillar twists upwards; the consequence is that the scaly legs and that part of the body to which they belong then ascend. When the last pair of legs is just over the jaws of the caterpillar, one leg, viz., that which is on the side towards which the head is inclined, seizes the thread and brings it over to the corresponding leg on the other side, which is advanced to receive it. If the head is then raised, which is done immediately, it is in order that it may seize the thread at a higher point than that at which it was caught at first; or, which is the same thing, the head, and consequently the whole body of the caterpillar, is found to have ascended to a height equal to the length of the thread which is between the place where its jaws seized it the first time and that where they seized it the second time. The first move in the upward direction is thus made, and the second soon follows.... If you were to seize the caterpillar on its arrival at the end of its upward journey, you would see a packet of threads huddled together between the four hindmost of the scaly legs. The greater the height ascended the greater is the size of this packet. All the turns of the thread which compose it are entangled. So the caterpillar does not consider it of any value. As soon as the insect can walk it gets rid of the mass, sets its legs free, and leaves it behind before one or at most two steps have been taken. The cord is wasted on each ascent, but the caterpillar can afford to lose as many as it likes, for it has in itself the source of the matter necessary for the composition of the thread, and it is a source from which that which was drawn off is being continually re-supplied. Moreover, spinning the thread costs the caterpillars but little; indeed, the loopers economise this thread so badly that most of them leave it behind them wherever they go.”
They are found on many trees, but particularly on the oak, the foliage of which they often entirely devour. They burrow into the ground to change into chrysalides, and undergo all their metamorphoses in the course of the year. Others do not become perfect insects till the autumn, or sometimes not even till the following spring. A few assume the perfect state in winter. There are, indeed, some of these, such as the males of the Hybernias, which fly about on the foggy evenings of November. The females of this genus have either no wings at all, or else only rudimentary ones. Two species, the Hybernia defoliaria, or Winter Moth, and the Chimatobia brumata, abundant here, are very common in the environs of Paris.
M. Maurice Girard says, in his work on the metamorphoses of insects, that the females of these moths can easily be found at the beginning of November, in a very strange place, namely, on the gas lamps of the public promenades; for instance, along the roads in the Bois de Boulogne. No doubt they had climbed up to this height, attracted by the light, or perhaps had been carried thither by the males, which fly, having wings.
In February and March appear other analogous species. “We may find,” says M. Maurice Girard, “near Paris, in the meadows which surround the confluence of the Seine and the Marne, at the end of the month of March, the Nyssia zonaria (Fig. 267), the males of which insect remain during the day motionless on the grass.” 72
There are some species of this family in which the wings of the females are developed like those of the males. 73 Such are thePeppered Moth (Amphidasis betularia) and the Currant Moth (Abraxas grossulariata), whose caterpillar lives on the red currant and gooseberry, and an immense number known as Thorns, Carpets, Waves, &c.
The section of the Pyralina contains the smallest nocturnal Lepidoptera, and nearly all those tiny species which flutter round our lights in the evening.
Here are some drawings of a few of the numerous species of this section, remarkable for their small size and beauty:—Penthina pruniana, Ædia pusiella, Xylopoda fabriciana, Pœdisca autumnana, Tortrix roborana, Philobacera fagana, Tortrix sorbiana, Antithesia salicana, Pœdisca occultana, Argyrolepia æneana, Sericoris Zinkenana, Sarrothripa revayana, Cochylis francilana, Choreutes dolosana (Figs. 268 to 281).74
In a book of this kind we can only mention some types among these last insects, which claim our attention in what we might almost call a tyrannical manner. We will, therefore, content ourselves by saying a few words about the Green Tortrix, the Pyralis of the Vine, the Bee-hive Moth, some species of the Clothes Moth family (Tineina), and finally of the Œcophoræ.
The Green Tortrix (Tortrix viridana) has wings of a green colour, with the margin and fringe whitish on the anterior, and of an ashy grey on the posterior wings. The under-side of the four wings is of a bright white, as if it had been silvered. This pretty moth comes out in the month of May. It is so common everywhere, that at this season it is only necessary to shake the branches of the oaks which border the alleys of the woods to set in motion hundreds of them. The caterpillar is green, with black warty spots, each having a hair of the same colour. They are wonderfully lively, the moment they are disturbed taking refuge in a rolled leaf, which serves them as a dwelling-place. If they are pursued, they let themselves fall by the aid of a thread, and do not re-ascend till they think they can count on repose and security. This, and many kindred species, do a great deal of damage to our trees. They strip them of their leaves, and sometimes give them, during the first days of summer, the sad and melancholy appearance which they present in the middle of winter.
We have just alluded to the tube formed of a rolled leaf, in which the caterpillar takes refuge, and in which it lives. This tube it constructs itself. Réaumur has devoted a magnificent chapter of his Memoirs to observations on the skill with which divers species of caterpillars fold, roll, and bind the leaves of plants and trees, especially those of the oak. Let us listen to the great observer:—“If one looks attentively at the leaves of the oak tree towards the middle of the spring, many of them will be seen to be rolled in different ways. The exterior surface of the end of one of these leaves has, it appears, been rolled back towards the interior surface, in order to describe the first turn of a spiral, which is then covered by many other turns (Fig. 282). Some leaves are rolled towards their exterior surfaces, others are rolled towards their interior surfaces, but in a totally different direction. The length or axis of the first roll is perpendicular to the principal rib and to the stalk of the leaf, the axis of the latter parallel to the same rib (Fig. 283). Work of this kind would not be very difficult to perform for those who had fingers; but caterpillars have neither fingers nor anything equivalent to fingers. Moreover, to have rolled the leaves is only to have done half the work: they must be retained in a position from which their natural spring tends constantly to draw them. The mechanism to which the caterpillars have recourse for this second part of their work is easily perceived. We see packets of threads attached by one end to the surface of the roll, and by the other to the flat surface of the leaf. They are so many bands, so many little cords which hold out against the spring of the leaf. There are sometimes more than from ten to twelve of these bands arranged nearly in the self-same straight line. Each band is a packet of threads of white silk, pressed one against the other, and yet we must remember all are separate.” 75
Réaumur made the oak-leaf rollers work in his house. He has admirably described all their little manœuvres, but we lack the space to convey to the reader the result of his minute observations. In fact, the leaf-rollers construct for themselves a sort of cylindrical cell, which receives light only through the two extremities. The convenience of this green fresh habitation is, that its walls furnish food to the animal which inhabits it. The caterpillar, thus sheltered, sets to work to gnaw away at the end of the leaf which it rolled first; it then eats all the rolls it has made, up to the very last.
Réaumur found also rolls which had been formed of two or three leaves rolled lengthwise, and he saw that the leaves which had occupied the centre had been almost entirely eaten. He saw also caterpillars which continued to eat while they were making their habitation. Let us add that one of the ends of the roll is the opening through which the caterpillar casts its excrement; that the caterpillar can prepare itself a fresh roll if it is turned out of the first; and, lastly, that it is in a rolled leaf that the caterpillar undergoes its metamorphoses into a chrysalis and into a moth.
Réaumur studied other leaf-rollers; for instance, those which roll the leaves of nettles and of sorrel. The last one works in a manner which deserves to be mentioned. Its roll is of no particular shape, but it is its position which is remarkable. It is set upon the leaf like a ninepin (Fig. 284). The caterpillar has not only to twist it up into a roll, but also to place it perpendicularly on the leaf.
Next to the rolling caterpillars, let us mention those which are contented with folding the leaves. These caterpillars then lie in a sort of flat box. Besides the rolling and folding caterpillars, there are still those which bind up a good many leaves in one packet. These packets are to be found on nearly every tree and shrub, and the caterpillar, lying nearly in the middle of the packet, is well sheltered, and surrounded by a good supply of food. We will content ourselves by giving a drawing, after Réaumur, of the pretty arrangement of the leaves of a species of willow (Figs. 285, 286). In the figures we see the parcel bound together by the caterpillar. In that to the right we see the transverse section of the packet of leaves magnified. At the two edges are seen the threads which keep the leaves together, and the cavity occupied by the caterpillar.
The Vine Pyralis is produced from a leaf-rolling caterpillar, which deserves our attention on account of the ravages which it has for some time committed, and which it still commits in vineyards. It was at the end of the sixteenth century that this pyralis first showed itself in the environs of Paris, in the territory of Argenteuil. “The inhabitants of this commune,” writes the Abbé Lebœuf, “looked on the insects which spoiled their vines in the spring of 1562 as a visitation of God. The Bishop of Paris gave orders that they should offer up public prayers for the diminution of these insects, and that they should join to their prayers, exorcisms, without leaving the church.” Prayers, processions, exorcisms, were again had recourse to in 1629, in 1717, and in 1733, to stop the ravages of this insect among the vines of Colombes, in the territory of Aï.
The country of the Mâconnais and the Beaujolais became in their turn the theatre of the ravages of the pyralis. These ravages very soon increased and spread. In 1836, 1837, 1838, this plague raged in the departments of the Saône-et-Loire, of the Rhône, of the Côte-d’Or, of the Marne, of the Seine-et-Oise, of the Charente-Inférieure, of the Haute-Garonne, of the Pyrénées-Orientales, and of the Hérault.
To give an idea of the losses which may be occasioned by the pyralis, in a period of ten years (1828-1837), twenty-three communes comprised in the two departments of the Saône-et-Loire and of the Rhône lost 75,000 hectolitres of wine a year, which may be valued at 1,500,000 francs. If we were to calculate the supply of articles of all sorts which this great number of casks of wine would have necessitated, the imposts on their transport, the duty, the taxes levied on their sale, the carriage by land and water, which would have brought receipts into the treasury, and lastly the diminution of taxes which had to be granted for seven years to the vine proprietors in the department of the Saône-et-Loire, and in 1837 in the department of the Rhône, and which amounted to a total of more than 100,000 francs, we shall find that the ravages of the pyralis caused in these two departments an annual loss of 3,408,000 francs, and as the visitation lasted ten years, we get the enormous sum total of 34,000,000 destroyed by the ravages of one species of insect. The moth of the pyralis (Fig. 287) shows itself from the 10th to the 20th of June. It is yellowish, more or less shot with gold. When at rest, its wings are folded back one over the other like a roof. Its flight is of short duration; it contents itself with going from one vine stock to another.
It is at sunset mostly that you see the moths of the pyralis fluttering about. They remain quiet during the day, particularly when the sun is at its hottest. They live on an average for ten days. The females lay their eggs—which are at first green, then yellowish, then brown—on the lower surface of the leaves.
The caterpillar of the pyralis (Fig. 288) is called, in vulgar parlance, according to the different places in which it occurs, vine worm, summer worm, vintage worm, shell. In the south of France it is called, in the patois of Languedoc, babota. Almost immediately after they leave the eggs, the little caterpillars hide themselves in the fissures of the vine stocks or the props which support them. They spin a small cocoon of a greyish silk, in which they remain curled up till the month of May. From the moment the leaves begin to develop they throw out threads here and there, entangling all the young shoots of the vine, which gives a desolate appearance to the vineyards. The leaves of the vine are their favourite food, but they attack the seeds of the grape also. As they increase in size every day, the damage they do goes on increasing, and has not reached the maximum of intensity till the moment when the caterpillars are about to change into chrysalides. They are then three-quarters of an inch long and of a yellowish green colour.
From the 20th of June to the 10th of July they seek shelter in the dry and interlaced leaves which have already served them for places of refuge and partly also for food, or else they make themselves a fresh nest.
At the end of two or three days, the caterpillar has become a chrysalis (Fig. 289), which in a short time assumes a brown colour. Shut up in the interior of the cocoon which the caterpillar had spun before undergoing its metamorphosis, it changes into a moth at the end of from fourteen to sixteen days.
The best way to diminish the ravages of the pyralis is to pluck off the leaves which are laden with eggs, and burn them, or bury them in deep holes.
Fig. 290, which we devote to the conspicuous insect whose destructive history we have been here able to sketch only slightly, gives all the particulars relating to this dangerous guest of the vineyards. On a branch of the vine may be perceived the pyralis in the caterpillar state, the eggs which have been laid by the moths, the chrysalides, and perfect insects. The eggs are shown at two periods of their development.
The Bee-hive or Wax Galleria is to be met with in all countries where bees are reared.
The moth (Fig. 291) hides itself during the day round about the bee-hives, and endeavours to make its way into them after sunset. The caterpillar is of a dirty white, with brown warty spots, each surmounted by a fine hair. It lives on wax, twines its threads round the honeycomb, and very soon causes the larvæ contained in it to perish.
When it emerges from the egg, which the female has laid in the honeycomb, the caterpillar makes for itself with the wax a round tube, in which it is safe against the stings of the bees. This tube, at first very small, is lengthened and enlarged as the caterpillar increases in size. It is generally from three to five inches in length. It is in the interior of this that the caterpillar constructs itself a hard cocoon, resembling leather, and it changes into a brownish chrysalis.
A species of the genus Butalis, the Butalis or Alucita granella, is, in certain cantons of France, one of the greatest pests to agriculture. The caterpillar of the Tinea granella undergoes its metamorphosis in the interior of grains of barley and of wheat, which it devours without being perceived from without. The female lays her eggs on the grains of corn before they are ripe. From four to six days after, the eggs are hatched, and the young caterpillars are hardly as thick as a hair. Each one takes possession of a grain of corn, and penetrates into it by an imperceptible opening. They eat the flower without injuring the teguments of the grain.
When it has attained its full size it spins itself a cocoon of white silk in the interior of the grain, which, after having been its lodging and its larder, becomes for some time its tomb. It has, however, taken care beforehand to make at the extremity of the grain a circular opening, through which the moth may come out when the grains have been threshed and stored up in the granary.
It is important to mention the Tineina, not because these little moths are beautiful—they are, on the contrary, very dingy—but because it is in this group that are found those insects which do the greatest damage to our crops. The moths of the genus Tinea are very small. Their wings, which are greyish or brownish, are generally marked with whitish and yellowish spots or lines. These are the little moths which, in our houses, burn themselves so frequently in the flames of the candles.
Their caterpillars are small, voracious, and deserve, on account of the damage which they cause, to be compared to rats and mice. Furnished with powerful jaws, they destroy everything they find in their way, such as woollen stuffs, hair, furs, feathers, grain, &c.
The Tineina are divisible into three groups: 1st, the species hurtful to our stuffs and furs; 2ndly, the species which destroy our corn crops; 3rdly, the phytophagous species, that is to say, those which feed on plants.
In the first subdivision must be classed the Fur Moth, the Woollen Moth, and the Hair Moth.
The Woollen Moth is represented in the figure on next page. Its caterpillar has the form of a worm, and is of a glossy whiteness, with a few hairs thinly sprinkled over it and a grey line on its back. It is enclosed in a tube, or sheath, open at both ends, in the interior of which is a sort of tissue of wool, sometimes blue, sometimes green, sometimes red, according to the colour of the stuff to which the insect attaches itself and which it despoils. The exterior of this sheath is, on the contrary, formed of silk made by the insect itself, of a whitish colour.
The caterpillars are hardly hatched before they begin to clothe themselves. Réaumur observed one of these worms during the operation of enlarging its case. To do this it put its head out of one of the extremities of its sheath, and looked about eagerly, to the right and to the left, for those bits of wool which suited it best for weaving in. In Fig. 294, we see two larvæ occupied in eating a piece of cloth.
“The larva changes its place continually and very quickly,” says Réaumur. “If the threads of wool which are near it are not such as it desires, it draws sometimes more than half its body out of its case to go and look for better ones farther off. If it finds a bit that pleases, the head remains fixed for an instant; it then seizes the thread with the two mandibles which are below its head, tears the bit out after redoubled efforts, and immediately carries it to the end of the tube against which it attaches it. It repeats many times in succession a similar manœuvre, sometimes coming partly out of its tube, and then again re-entering it to fix against one of its sides a new piece of wool.”
After having worked for about a minute at one end of its tube, it thinks of lengthening the other. It turns itself round in its tube with such quickness, that you would imagine it could not have had time to do so, and would think that its tail was formed in the same way as its head, and possessed the same address in choosing and tearing out the bits of wool.
Furthermore, when the moth which is working at elongating its case does not find the threads or hairs of wool to its taste within reach of its head, it changes its place. Réaumur saw this insect walking, at some speed even, carrying with it its case. It walks on its six front legs (Fig. 295). With the middle and hind legs it clings to the interior of its case.
At the same time that the larva becomes longer it becomes stouter. Very soon its garment will be too narrow for it. Will it enlarge its old coat, or will it make itself a new one? Réaumur discovered that it preferred to widen its old coat.
That is what our naturalist saw when he placed larvæ with blue cases, for instance, upon stuff of a red colour. The bands which extended in straight lines from one end of the case to the other, showed the part that had been added.
“From watching them at different times,” says this admirable observer, “I find that the means which they employ is precisely that to which we should have had recourse in a similar case. We know of no other way of widening a sheath, a case of any stuff that we find too narrow, than to split it right up and to let in a piece of the proper size between the parts which we have thus divided; we should let in a piece on each side if the shape of the tube seemed to require it. This is also exactly what our larvæ do, with an extra, and which with them is a necessary, precaution, so as not to remain exposed while they are working at the enlargement of their garment. Instead of two pieces, which should each be as long as their case, they let in four, each of which is not longer than half the length of their case; and so they never split up more than half the length of the case at the same time, which has enough stuff left in it to keep it together while this opening is being filled up.”
The wools of our stuffs furnish the moths not only with clothing, but also with food. Their excrements are little grains, which are the same colour as the wool they have eaten.
When they are full grown, and the time approaches for their metamorphosis, the larvæ abandon their food, and establish themselves in the angles of walls. They creep up to the ceilings and suspend themselves to them by one extremity of their tube. The two ends of the tube are now closed by a silken tissue (Fig. 296). The larva thus enclosed very soon changes its form; it becomes a chrysalis; then at the end of about three weeks it is set free as a moth.
The Fur or Skin Moth works like the carpet moth: it makes itself a case of the same form, and constructs it in the same manner. Only in this case its covering is made of a sort of felt resembling that of which our hats are made.
While the Carpet Moth only detaches from the various stuffs the wool it requires for clothing and nourishment, the Fur Moth causes much more considerable and more rapid damage. It cuts off all the hairs which are in its way right down to the skin; it seems as if it took a delight in cutting them off. That which is necessary for its wants is nothing in comparison to the great quantity of hair one sees fall off a skin on which it has established itself, when it is shaken. As it advances it cuts more thoroughly than a razor could all the hairs which are in its way.
The Hair Moth (Fig. 297) shows itself in great numbers in the perfect state, from the end of April till the beginning of June. They appear again in September, and generally stay behind cabinets and other pieces of furniture.
The caterpillar, which is cylindrical, white, destitute of hair, and striped with brown, lives principally in the hair with which furniture is stuffed, and sometimes in hair mattresses. When it has reached its full size, it abandons its abode, pierces through the stuff which covers the hair, and constructs for itself with this stuff a case of silk, open only towards the end where the head is. At the beginning of April it shuts its case, and changes itself into a chrysalis.
We can only here mention some of the phytophagous species, as the Cherry-tree Moth (Tinea cerasiella), the Hawthorn Moth (Tinea cratægella), the Burdock Moth (Tinea lapella), and the Rustic Moth (Tinea rusticella).
The caterpillars of the Œcophoræ resemble whitish worms. They attack the leaves, the blossoms, the bark, and certain parts of the fruit of trees. Some of these hollow out for themselves galleries in eating the fleshy part; others also make galleries, but only in the cuticle of the tree, or in the tenderest part of its bark. Some, again, shut themselves up in one or many leaves rolled like a trumpet, while others keep at the summits of plants, whose leaves they bind together in a parcel with threads. And, lastly, some devour the stones of fruits, such as that of the olive.
The moths of these caterpillars are very small, and generally of brilliant metallic colours, they are to be found in the woods, and still more in the orchards, from the beginning of June till the month of September.
The Œcophoræ are very slim and elegantly formed. Their anterior wings, which are very narrow, are often ornamented with silvery longitudinal lines, the posterior wings exactly resembling two feathers.
The caterpillars live and metamorphose themselves in portable cases, which they manufacture from the membranous portions of leaves, whose flesh alone they eat. These cases are generally of a brown colour, resembling a dead leaf. They are attached perpendicularly under the leaves of many trees, but often under those of fruit trees.
Certain species of Œcophoræ have cases partly covered with loose pieces only slightly attached, formed of portions of leaves, and arranged in such a way that Réaumur compares them to the furbelows which ladies used formerly to attach to the bottom of their dresses.