III Hemiptera
The Hemiptera are particularly distinguished from other kinds of insects by the form of their mouth, which consists of a beak, more or less long, composed of six parts: that is, of a lower lip, or sheath; four internal threads, representing the mandibles and jaws of the grinding insects, and which are the perforating parts of the beaks; and, lastly, of the upper lip or labrum. Owing to this apparatus, these insects are essentially sucking ones, and chiefly nourish themselves with the juices of vegetables, which they draw up with their beak. The wings of the Hemiptera are usually four in number; in some species they are membranous and similar to each other, and in others the upper are of rather harder consistency than the lower ones. In general, the former are quite different from the lower wings, and are only membranous at the tip, whereas the other part is thick, tough, and coriaceous.
The Hemiptera are divided into two very distinct sections. The one is composed of insects whose beak grows from the forehead or upper part of the head, and whose anterior wings are half coriaceous and half membranous, having the base of a different texture from the extremity: these are the Heteroptera (ἑτερος, different; πτερον, wing). The other section is composed of those whose beak grows from the lower part of the head, and whose anterior wings are always of the same consistency throughout: these are the Homoptera (ὁμος, the same; πτερον, wing). We are about to give the history of these two sub-orders.
The insects formerly known by the general name of Bugs have been divided by Latreille into two large families, containing: the one the Geocorisæ, 19 or Land Bugs; the other the Hydrocorisæ, 20 or Water Bugs.
The land bugs consist of a great number of kinds, which, for the most part, are of little interest. We will only mention here the Peniatomidæ, commonly known as Wood Bugs; the Lygæi, Bugs, properly so called; the Reduvii, and the Hydrometræ.
The Pentatomidæ, which comprise many genera, include the wood bugs of most authors. They are to be found on plants and trees. They fly quickly, but only for a short time.
The Ornamented Pentatoma (Strachia [Pentatoma] ornata), known as the Red Cabbage Bug, is very commonly found on the cabbage, and on most of the cruciferous plants. It is variegated with red and black, and its colours are subject to numerous variations. The Grey Pentatoma (Raphigaster griseus), Fig. 69, is common throughout the whole of Europe. In autumn these bugs are frequently to be found on raspberries, to which they impart their disagreeable smell. They are also to be found in quantities on the mullein, when that plant is in flower. The upper parts of the head are of a greyish brown, and are sometimes slightly purple. The coriaceous part of the hemelytra is of a purple tint, but the membranous part is brown. All these parts are covered with black spots, which are only to be seen with a magnifying-glass. The wings are blackish. The under part of the whole body and the feet are of a light and rather yellowish grey, with a considerable number of small black spots. The abdomen is black above; and it is bordered with alternate black and white spots.
We have repeated here the description given of this bug by the illustrious Swedish naturalist, De Geer, because our young readers have most likely met with this insect, or will do so some day when gathering raspberries.
The Grey Pentatoma, marked with black, yellow, and red, is to be found throughout the whole of Europe in cultivated fields and gardens, sometimes also on the trunks of large trees, especially elms. This species, in common with the greater part of those which compose the group we are describing, emits a smell when irritated or menaced by some danger. At other times no odour will be noticed. Let us hear what M. Léon Dufour says on this subject.
“Seize the Pentatoma with a pair of pincers and plunge it into a glass of clear water; look through a magnifying-glass, and you will see innumerable small globules arising from its body, which, bursting on the surface of the water, exhale that odour which is so disagreeable. This vapour, which is essentially acrid, if it happens to touch the eyes, causes a considerable amount of irritation. If one of these insects is held between the fingers, so as not to stop up the odoriferous orifices, and to cause this vapour to touch a part of the skin, a spot, either brown or livid, will ensue on that part, which lotions, though repeatedly applied, will at first fail to remove, and which produces in the cutaneous tissue an alteration similar to that which succeeds the application of mineral acids.”
The disagreeable smell exhaled by different species of Pentatoma is the result of a fluid secreted by a single pear-shaped gland, either red or yellow, which occupies the centre of the thorax, and which terminates between the hind legs.
With the Syromastes, which are bugs of this same section, the secretion has, on the contrary, an agreeable smell, which reminds one of that of apples. Many kinds of Pentatoma are destructive to agriculture. Others, however, attack the destructive insects, and ought therefore to be carefully spared. We will mention in this case the Blue Pentatoma, which kills the Altica 21 of the vine.
There may be observed, at the foot and about the lower part of trees, or at the base of walls exposed to the mid-day sun, groups of fifty or sixty small insects pressed close to each other, and often one on the top of the other, their heads in the direction of a centre point. They are red, spotted with black. In the neighbourhood of Paris the children call them “Suisses,” probably on account of the red on their bodies, that being the colour of the uniform of the Swiss troops formerly in the service of France. In Burgundy the children call them “petits cochons rouges.” They will be found described in Geoffroy’s “Histoire des Insectes,” under the name of the Red Garden Bug. At the present day they are placed in the genus Lygæus.22 When the bad weather comes, these little “Suisses” take refuge under stones and the bark of trees to pass the winter. During the whole of that season they remain in a sort of torpid state. But in the first days of spring they revive, and resume their ordinary habits. They suck the sap of vegetables, piercing the capsules of divers kinds of mallows, and always keeping in the sunshine.
The Bug, popularly so called, or Bed Bug (Acanthia lectularia, or Cimex lectularius, Fig. 70), a most disagreeable and stinking insect, abounds in dirty houses, principally in towns, and above all in those of warm countries. It lives in beds, in wood-work, and paper-hangings. There is no crack, however narrow it may be, into which it is unable to slip. It is nocturnal, shunning the light. “Nocturnum fœtidum animal,” says Linnæus. Its body is oval, about the fifth of an inch in length, flat, soft, of a brown colour, and covered with little hairs. Its head is provided with two hairy antennæ, and two round black eyes, and has a short beak, curved directly under its thorax, and lying in a shallow groove when the animal is at rest. This beak, composed of three joints, contains four thin, straight, and sharp hairs. The thorax is dilated at the sides. The abdomen is very much developed, orbicular, composed of eight segments, very much depressed, and easily crushed by the fingers. The hemelytra are rudimentary. It has no membranous wings. The tarsi have three articulations, of which the last is provided with two strong hooks.
“These animals,” says Moquin-Tandon, in his “Zoologie Médicale,” “do not draw up the sanguineous fluid by suction, properly so-called, as leeches do. The organisation of their buccal apparatus does not allow of this. The hairs of the beak applied the one against the other exercise a sort of alternate motion, which draws the blood up into the œsophagus, very much in the same manner as water rises in a chain pump. This rising is assisted by the viscous nature of the fluid, and above all, by the globules it contains.” The part of the skin which the Bug has pierced, producing a painful sensation, is easily recognised by a little reddish mark, presenting in its centre a dark spot. Generally a little blister rises on the point pierced, and sometimes, if the Bug-bites are numerous, these blisters become confluent, and resemble a sort of eruption. These disgusting insects lay, towards the month of May, oblong whitish eggs (Fig. 71), having a small aperture, through which the larva comes out. The larva differs from the insect in its perfect state, in its colour, which is pale or yellowish. This insect exists in nearly the whole of Europe, although it is rare or almost unknown in the northern parts. The towns of central Europe are the most infested by this parasite, but those of the north are not completely free from its presence. The Marquis de Custine assures us that at St. Petersburg he found them numerous. It is found also in Scotland; is very rare in the south of Europe; and seldom seen in Italy, where it is, however, replaced by other insects more dangerous or more annoying.
It has been said that the Bug was brought into Europe from America; but Aristotle, Pliny, and Dioscorides mention its existence. It is certain that it was unknown in England till the beginning of the sixteenth century. A celebrated traveller, a Spanish naturalist, Azara, has remarked that the Bug does not infest man in his savage state, but only when congregated together in a state of civilisation, and in houses, as in Europe. From this he concluded that the Bug was not created till long after man, when, after many centuries had elapsed since his appearance on the globe, men formed themselves into societies, into republics, or little states.
The bug is not a gluttonous insect, always bloodthirsty; on the contrary, its sobriety is remarkable. It is only after a prolonged fast that it bites animals; and Audouin has stated that it can live a year and even two years without food.
From time immemorial a number of different means have been employed for destroying these insects; but in spite of all, nothing is more difficult than to get rid of them from wood-work and paper-hangings, when they have once infested them. In general, strong odours cause their death. And so, to rid oneself of these disagreeable guests, it has been recommended to use tobacco smoke, essence of turpentine, the fumes of sulphur, &c. Mercurial ointment and corrosive sublimate are also excellent means for their destruction; and for the same purpose the merits of a plant belonging to the order Cruciferæ, Lepidium ruderale, have been much vaunted; and more recently still, the root of the Pyrethrum, a species of camomile, reduced to powder, and blown into the furniture or wood-work. This powder is known and employed at Paris under the name of “poudre insecticide.”
There are two other kinds of bugs (Acanthia) which attack men. The one is the Acanthia ciliata, which has been found in the houses of Kazan, and which differs from the bed bug not only in its form, but also in its habits. It does not live in companies, in the narrow cracks of furniture, but moves about alone, at a slow pace, over walls or the counterpanes of beds. Its beak is very long, and its bite is very painful, and produces obstinate swellings.
The other species is the Acanthia rotundata, which is found in the Island of La Réunion, and attacks men in the same way as does the European bug. Two species of the same genus live as parasites on swallows and domestic pigeons. There is another species, which is peculiar to the bats of our climates.
The Reduvius personatus, called also Fly Bug, by Geoffroy, the old historian of the insects of the environs of Paris, is common enough in France. It keeps to the houses, and is found especially near ovens and chimney-pieces. It is about three-quarters of an inch in length, oblong, flat on its upper side, brownish, has horizontal hemelytra crossed over each other, and very fully developed wings, which serve for flight. Its head, narrow, supported by a well-defined neck, is provided with two composite and two simple eyes. It requires, no doubt, to see very clearly, as it flies by night. It should not be caught without great caution. If you desire to examine it closely, when, in the hottest part of the summer, it comes in the evening and flutters round the lights, you must be careful how you seize it, for it wounds. The wounds inflicted by it are very painful—more painful than those of the bee—and they immediately cause a numbness.
As the Reduvius kills different insects very rapidly, by piercing them with its long beak, it is probable that it secretes some kind of venom. But as yet the organ that produces this poison has not been discovered. However that may be, its beak is curved, and about the tenth of an inch long, the surface bristling with hairs. It is composed of three joints, and contains four stiff, lanceolate, and very pointed squamose hairs.
This insect often seeks its prey in places where spiders spin their webs. When they walk on, or are caught in, the spiders’ webs, the spiders take care not to seize them, for they fear their beak. They prudently allow them to struggle about the nets, where they very soon die of hunger. The Reduvius is often seen, either a prisoner or dead, in the midst of a spider’s web.
“This bug,” says Charles de Geer, “has, in the pupal condition, or before its wings are developed, an appearance altogether hideous and revolting. One would take it, at the first glance, for one of the ugliest of spiders. That which above all renders it so disagreeable to the sight is that it is entirely covered, and, as it were, enveloped with a greyish matter, which is nothing else but the dust which one sees in the corners of badly-swept rooms, and which is generally mixed with sand and particles of wool, or silk, or other similar matters which come from furniture and clothes, rendering the legs of this insect thick and deformed, and giving to its whole body a very singular appearance.”
What instincts! what habits! Under this borrowed costume, under this cloak, which is no part of itself, the insect, as it were, masked, has become twice its real size. What becomes of its disguise, and how does it manage to walk? Of what use to it is this dirty and grotesque fancy dress?
Let us listen to De Geer. “It walks as fast, when it likes, as other bugs; but generally its walk is slow, and it moves with measured steps. After having taken one step forward, it stops a while, and then takes another, leaving, at each movement, the opposite leg in repose; it goes on thus continually, step after step in succession, which gives it the appearance of walking as if by jerks, and in measure. It makes almost the same sort of movement with its antennæ, which it moves also at intervals and by jerks. All these movements have a more singular appearance than it is possible for us to describe.”23
By means of this disguise, it can approach little animals, which become its prey, such as flies, spiders, bed bugs.
To see what a curious appearance the Reduvius presents, one should take off its borrowed costume. Then you will observe an entirely different animal, and one which has nothing repulsive about it. With the exception of the hemelytra and wings, which it has not yet got, all its parts have the form which they are to have later, after the wings are developed.
Fig. 72 represents, from Charles de Geer’s Memoir, the pupa of the Reduvius personatus covered with dust, and resembling a spider; Fig. 73 the same insect cleaned, freed from the cloak of dust which served to disguise it.
The Hydrometræ (from ὑδωρ, water, and μετρειν, to measure) have linear bodies. The head, which forms nearly the third of the entire length, is furnished with two long antennæ, and armed with a thin, hair-like beak. The legs are long, and of equal length. The reader may have often seen the Hydrometra stagnorum walking by jerks on the surface of the water (Fig. 74). The body and legs are of a ferruginous colour, the hemelytra a dull brown, and the wings hyaline, or glassy, and slightly blackish. Geoffroy says that it resembles a long needle, and calls it the Needle Bug.
The Hydrocorisæ, or Water Bugs, have the antennæ shorter than the head, or scarcely attaining to its length, and inserted and hidden under the eyes, which are in general of remarkable size. All these Hemiptera are aquatic and carnivorous. We will mention the two principal types, the Nepæ, or Water Scorpions, and the Notonectæ, or Boatmen.
The Nepa cinerea (Fig. 75), which Geoffroy calls the Oval-bodied Water Scorpion, and which he also designates by the name of the Water Spider, is very common in the stagnant waters of ponds and ditches. Its body, oval, very flat, of an ashy colour, with red on the abdomen, is four-fifths of an inch long. The hemelytra are horizontal, coriaceous, and of a dirty grey colour. Its front legs, with short haunches, and very broad thighs, are terminated by strong pincers, which give to the insect a strong resemblance to the scorpion. It is by folding back the leg and the tarsus under the thigh, that the animal holds its prey, and sucks it with its rostrum or beak.
This rostrum is composed of three joints, and contains four pointed bristles. Two present on one side a sort of narrow sharp blade, and have teeth towards their base. Of the two others, the one is a thin smooth needle, the other is provided with hairs directed backwards and forwards.
It is with this rostrum, which resembles a case of surgical instruments, that the Nepa pierces and sucks little aquatic insects, not even sparing its own species. Its wound is painful to man, but not in the least dangerous. With its four hind legs the Nepa swims, but at a very slow pace. It generally drags itself along the bottom of the water, on the mud, and does not avoid the hand put out to seize it. Its body is terminated by a tail, composed of two grooved threads, which, when applied together, form a tube, capable of being moved from side to side. Through this canal it breathes the outer air; it puts the end of it out of the water, and the air enters it by inspiration. Some very small hairs, with which the interiors of the grooves are lined, interlace each other, and prevent the water from penetrating into the canal. It is probable that this same canal serves also for depositing the eggs. These last resemble small seeds, covered with points, and are buried in the stalks of aquatic plants.
Next to the Nepa comes the Ranatra, with a cylindrical, elongated, linear body, with very long and very thin hind legs, and of which one species, which Geoffroy calls the “aquatic scorpion with an elongated body,” is common everywhere in stagnant waters in spring. It is brownish, carnivorous, and very voracious.
We must now mention the genus Corixa, of which one species, the Corixa striata, is very common. This insect walks badly and slowly on land, but swims and cuts through the water with a prodigious rapidity.
However, it is not to delay over this last species that we have here mentioned the name of this genus. Some insects which belong to it, and which are found in Mexico, deserve to be alluded to, on account of certain peculiarities which their eggs present. A naturalist, M. Virlet d’Aoust, has published the following details on this subject:—
“Thousands of small amphibious flies,” he says, “flit about in the air on the surface of lakes, and diving down into the water many feet, and even many fathoms, go to the bottom to lay their eggs, and only emerge from the water probably to die close by. We were fortunate enough to be present at a great fishing or harvest of the eggs, which, under the Mexican name of hautle (haoutle), serve for food to the Indians, who seem to be no less fond of them than the Chinese are of their swallows’ nests, which they resemble somewhat in taste; only the hautle is far from commanding such high prices as the Chinese pay for their birds’ nests, which for that reason are reserved entirely for the tables of the rich; while, for a few small coins, we were able to carry away with us about a bushel of the hautle, a portion of which, at our request, Mme. B—— was kind enough to prepare for us.
“They dress these in different ways, but generally make a sort of cake, which is served up with a sauce, to which the Mexicans give a zest, as they do indeed to all their dishes, by adding to it chilié, which is composed of green pimento crushed. This is how the natives proceed when they are fishing for hautle: they form with reeds bent together a sort of fasces, which they place vertically in the lake at some distance from the bank, and as these are bound together by one of the reeds, the ends of which are so arranged as to form an indicating buoy, it is easy to draw them out at will. Twelve to fifteen days suffice for each reed in these fasces to be entirely covered with eggs, which they thus fish up by millions. The former are then left to dry in the sun, on a cloth, for an hour or more; the grains are then easily detached. After this operation, they are replaced in the water for the next hautle harvest.”
M. Virlet had attributed to flies the eggs of which we have been speaking. But in 1851 M. Guérin-Méneville having received, transmitted to him by M. Ghiliani, eggs of which hautle is made, and some of the insects said to produce them, stated that the latter belonged to two different species. The one had been known a long time since under the name of Corixa mercenaria; M. Guérin-Méneville called the other Corixa femorata.
The same entomologist discovered, among the eggs of these two species, other eggs of a more considerable size, and which he attributed to a new species of the genus Notonecta, about which we are now going to say a few words.
The Notonecta glauca, which Geoffroy calls the Large Bug with Oars (“Grande punaise à avirons”), is very common in ditches, reservoirs, and stagnant waters. Its body is oblong, narrow, contracted posteriorly, convex above, flat below, having, at its sides and its extremities, hairs which, when spread out, support the animal on the water. Its head is large and of a slightly greenish grey, and has on each of its sides a very large eye of a pale brown colour. Its thorax is greyish, the hemelytra of a greenish grey, the membranous wings white. Of its legs, the front four are short; but the hind legs, almost twice as long, are furnished with long hairs, and resemble oars. It is with the aid of these that the animal moves through the water; and it does so in a singular manner, placing itself on its back, and generally in an inclined position, as in Fig. 77.
When this insect, on the contrary, drags itself along on the mud, the front legs are those which it employs, the hind legs being idle, and merely drawn along behind it. It is generally towards the evening or during the night that it comes out of the water, to walk and to fly, if it wishes to pass from one marsh to another.
This bloodthirsty insect lives entirely by rapine; it is one of the most carnivorous of insects. Those which it attacks die very soon after they have been hurt by it. De Geer thinks that the water bug drops into the wound a poisonous humour. It seizes upon insects much bigger, and apparently much stronger, than itself, and does not spare its own species.
The instrument with which the Notonecta attacks its prey is composed of a very strong and very long conical beak, formed of four joints. The sucker is composed of an upper piece, short and pointed, and of four fine pointed hairs.
The female of the Notonecta glauca lays a great number of eggs, white, and of elongated shape, which it deposits on the stems and leaves of aquatic plants. The eggs are hatched at the beginning of spring, or in May, and the young ones at once begin to swim about like their mother, on their backs, belly upwards. M. Léon Dufour says on this subject:—
“A dorsal region, raised like a donkey’s back, or like the rounded keel of a boat, and covered with a velvety substance, which renders it impermeable, numerous fine fringes which garnish either the hind legs, or the borders of the abdomen and thorax, or lastly in a double row form a crest or comb running down the surface of the belly, and which spread themselves out or fold themselves in at the will of the insect, just like fins, favour both this supine attitude and the accuracy of the swimming movements of the Notonectæ. Since Nature—which seems often to delight in producing extraordinary exceptions to her ordinary rules, thus bearing witness to the immensity of her resources—had condemned this animal to pass its life in an inverted position, it was necessary, for the maintenance of its existence, that it should provide it with an organisation in harmony with this attitude. It is also for this object that its head is bent over its chest; that its eyes, of an oval shape, can see below from above; that the front as well as the middle legs, agile and curved, solely destined for prehension, can to a certain extent become unbent by means of the elongated haunches which fix them to the body, and clutch firm hold of their prey with the strong claws which terminate the tarsi.”
We come now to the second group of the order Hemiptera, namely, Homoptera.
The insects which compose this division are numerous. They may be arranged into three great families, of the most remarkable members of which we shall give some account. These are the Cicadæ, the Aphidæ or Plant Lice, and the Coccidæ.
The Cicada is the type of the first of these families. It has a deafening and monotonous song; as Bilboquet says, in the “Saltimbanques,” “those who like that note have enough of it for their money.” Virgil pronounced a just criticism on the song of the Cicada: he saw in it nothing better than a hoarse and disagreeable sound:—
“At mecum raucis, tua dum vestigia lustro,
Sole sub ardenti resonant arbusta cicadis,”
says the Latin poet in his “Eclogues,” and repeats the same opinion in a verse in his “Georgics:”—
“Et cantu querulæ rumpent arbusta cicadæ.”
The song of the Cicada, so sharp, so discordant, was, however, the delight of the Greeks.
Listen to Plato in the first lines of “Phædo:” “By Hera,” cries the philosopher-poet, “what a charming place for repose!... It might well be consecrated to some nymphs and to the river Achelöu, to judge by these figures and statues. Taste a little the good air one breathes. How charming, how sweet! One hears as a summer noise an harmonious murmur accompanying the chorus of the Cicada.”
The Greeks, then, had quite a peculiar taste for the song of the Cicada. They liked to hear its screeching notes, sharp as a point of steel. To enjoy it quite at their ease they shut them up in open wicker-work cages, pretty much in the same way as children shut up the cricket, so as to hear its joyous cri-cri. They carried their love for this insect with the screaming voice so far as to make it the symbol of music. We see, in drawings emblematical of the musical art, a Cicada resting on strings of a cythera. A Grecian legend relates that one day two cythera players, Eunomos and Aristo, contending on this sonorous instrument, one of the strings of the former’s cythera having broken, a Cicada settled on it, and sang so well in place of the broken cord, that Eunomos gained the victory, thanks to this unexpected assistant. Anacreon composed an ode in honour of the Cicada. “Happy Cicada, that on the highest branches of the trees, having drank a little dew, singest like a queen! Thy realm is all thou seest in the fields, all which grows in the forests. Thou art beloved by the labourer; no one harms thee; the mortals respect thee as the sweet harbinger of summer. Thou art cherished by the muses, cherished by Phœbus himself, who has given thee thy harmonious song. Old age does not oppress thee. O good little animal, sprung from the bosom of the earth, loving song, free from suffering, that hast neither blood nor flesh, what is there prevents thee from being a god?”
It was in virtue of the false ideas of the Greeks on natural history in general, and on the Cicada in particular, that this little animal symbolised, among the Athenians, nobility of race. They imagined that the Cicada was formed at the expense of the earth, and in its bosom, on which account those who pretended to an ancient and high origin, wore in their hair a golden Cicada. The Locrians had on their coins the image of a Cicada. This is the origin which fable assigns to the custom:—
The bank of the river upon which Locris was built was covered with screeching legions of Cicadas; whereas they were never heard (so says the legend) on the opposite bank, on which stood the town Rhegium. In explanation of this circumstance, they pretend that Hercules, wishing one day to sleep on this bank, was so tormented by the “sweet eloquence” of the Cicadas, that, furious at their concert, he asked of the gods that they should never sing there for evermore, and his prayer was immediately granted! This is why the Locrians adopted the Cicada as the arms of their city.
The Greeks did not only delight, as poets and musicians, in the song of the Cicada; they were not content with addressing to it poems, with adoring it, and striking medals bearing its image; obedient to their grosser appetites, they ate it. They thus satisfied at the same time both the mind, the spirit, and the body.
The Cicadas are easily to be recognised by their heavy, very robust, and rather thick-set bodies, by their broad head, unprolonged, having very large and prominent ocelli, or simple eyes, three in number, arranged in a triangle on the top of the forehead, and short antennæ. The immature anterior and posterior wings have the shape of a sheath, or case, enveloping the body when the insect is at rest; these are transparent and destitute of colour, or sometimes adorned with bright and varied hues. The legs are not in the least suited for jumping. The female is provided with an auger, with which she makes holes in the bark of trees in which to lay her eggs. The male (Fig. 78) is provided with an organ, not of song, but of stridulation or screeching, which is very rudimentary in the female. We will stop a moment to consider the apparatus for producing the song, or rather the noise, of the male Cicada, and the structure of the female’s auger. We are indebted to Réaumur for the discovery of the mechanism by the aid of which the Cicada produces the sharp noise which announces its whereabouts from afar. We will give a summary of the celebrated Memoir in which the French naturalist has so admirably described the musical apparatus of the Cicada. 24
It is not in the throat that the Cicada’s organ of sound is placed, but on the abdomen. On examining the abdomen of the male of a large species of Cicada, one remarks on it two horny plates, of pretty good size, which are not found on the females. Each plate has one side straight; the rest of its outline is rounded. It is by the side which is rectilinear that the plate is fixed immediately underneath the third pair of legs. It can be slightly raised, with an effort, by two spine-like processes, each of which presses upon one of the plates, and when it is raised, prevents it from being raised too much, and causes it to fall back again immediately.
If the two plates are removed and turned over on the thorax, and the parts which they hide laid bare, one is struck by the appearance which is presented. “One cannot doubt that all one sees has been made to enable the Cicada to sing,” says Réaumur. “When one compares the parts which have been arranged so that it may be able to sing, as we may say, from its belly, with the organs of our throat, one finds that ours have not been made with more care than those by means of which the Cicada gives forth sounds which are not always agreeable.”
We here perceive a cavity in the anterior portion of the abdomen and which is divided into two principal cells by a horny triangle.
“The bottom of each cell offers to children who catch the Cicada a spectacle which amuses them, and which may be admired by men who know how to make the best use of their reason. The children think they see a little mirror of the thinnest and most transparent glass, or that a little blade of the most beautiful talc is set in the bottom of each of these little cells. That which one might see if this were the case would in no way differ from what one actually sees; the membrane which is stretched out at the bottom of the cells does not yield in transparency either to glass or to talc; and if one looks at it obliquely, one sees in it all the beautiful colours of the rainbow. It seems as if the Cicada has two glazed windows through which one can see into the interior of its body.”
The horny triangle of which we spoke above only separates in two the lower part of the cavity. The upper part is filled by a white, thin, but strong membrane. This membrane is only drawn tight when the body of the Cicada is raised. But with all this, where is the organ of song? What parts produce the sound? Réaumur will enlighten us on this point.
He opened the back of a Cicada, and laid bare the portion of the interior which corresponds with the cavity where the mirrors are, and was immediately struck with the size of the two muscles which meet and are attached to the back of the horny triangle, and to that one of its angles from which start the sides which form the cavities in which are both the mirrors.
“Muscles of such strength, placed in the belly of the Cicada, and in that part of the belly in which they are found, seem to be only so placed in order that they may move quickly backwards and forwards those parts which, being set in motion, produce the noise or song. And indeed, whilst I was examining one of these muscles, in moving it about gently with a pin, slightly displacing it, and then letting it return to its proper place, it so happened that I made a Cicada that had been dead for many months sing. The song, as might be expected, was not loud; but it was strong enough to lead me on to the discovery of the part to which it was due. I had only to follow the muscle I had been moving, to search for the part on which it abutted.”
In the large cavity, in which are the mirrors and the other parts mentioned above, there are besides two equal and similar compartments, two cells, in which are placed the instrument of sound. This is a membrane in the shape of a kettledrum, not smooth, but, on the contrary, crumpled and full of wrinkles (Fig. 79). When it is touched it is more sonorous than the driest parchment. If the furrows on its convex surface are rubbed with a small body, such as a piece of rolled-up paper, incapable of piercing or tearing it, it is easily made to sound; and the sound is occasioned by the portions of the kettledrum which are depressed by the friction of the small body, returning to their former position as soon as it has ceased to act upon them. It is here that the two strong muscles act whose existence and use were discovered by Réaumur.
“It is clear,” says this naturalist, “that when the muscle is alternately contracted and expanded with rapidity, one convex portion of the kettledrum will be rendered concave, and will then resume its convex form by the force of its own spring. Then this noise will be made, this song of which we have been so long seeking an explanation, because we wished to find out all the parts by means of which He, who never makes anything without its use, willed that it should be produced.”
Let us add, to complete what we have already said on this subject, that if the kettledrums are the essential organs of the insect’s song, the mirrors, the white and wrinkled membranes, and the exterior shutters which cover in the whole apparatus, contribute largely, as Réaumur pointed out, to modify and strengthen the sound.
We have said above that the female Cicada does not sing; and so her singing organs are quite rudimentary. This fact, moreover, has been known for ages. Xenarchus, a poet of Rhodes, says, with little gallantry:—
“Happy Cicadas! thy females are deprived of voice!”
Nature has indemnified the female Cicada for this privation, by giving her an instrument less noisy indeed, but more useful. This is a sort of auger, destined to penetrate the bark of the branches of trees, and lodged in the last segment of the abdomen, which, for this purpose, is hollowed out groove-wise. By the aid of a system of muscles the auger can be protruded or retracted at pleasure. It is furnished with three implements. In the middle there is a piercer, or bodkin, which when run into a branch supports the insect, and two stylets, whose upper edges, having teeth like a saw, resting back to back, on the middle implement, move up and down it. With this admirable instrument the female Cicada incises obliquely the bark and wood until she has almost reached the pith (Fig. 80). The male sings while she is at work. When the cell is sufficiently deep and properly prepared, the female lays at the bottom of it from five to eight eggs.
From these eggs come very small white grubs (Fig. 81), which leave their nest, descend by the trunk, and bury themselves in the ground, where they devour the roots of the tree. They then become pupæ, and hollowing out the earth with their front legs, which are very much developed, continue to live at the expense of the roots. At the end of spring these pupæ (Fig. 82) come out of the earth, hook themselves on to the trunks of trees, and strip themselves one fine evening of their skin, which remains whole and dried. Very weak at first, these metamorphosed insects drag themselves along with difficulty. But next day, warmed by the first rays of the sun, having had, no doubt, time to reflect on their new social position, and less astonished than they were on the preceding evening, they agitate their wings, they fly, and the males send forth into the air the first notes of their screeching concert. The Cicadas remain on trees, whose sap they suck by means of their sharp-pointed beak. It is difficult enough to catch them, for owing to their large, highly-developed wings, they fly rapidly away on the slightest noise.
They inhabit the south of Europe, the whole of Africa from north to south, America in the same latitudes as Europe, the whole of the centre and south of Asia, New Holland, and the islands of Oceania. The Cicada, which in hot climates always exposes itself to the ardour of the most scorching sun, is not found in temperate or cold regions. The consequence is that the southern nations know it very well, whilst in the north the large grasshopper, which is so common in those regions, and whose song closely resembles that of the Cicada, is commonly taken for it. There was to be seen at the Exhibition of Fine Arts in 1866 a picture by M. Aussandon, “La Cigale et la Fourmi,” which showed, under an allegorical shape, the subject of La Fontaine’s fable. The painter here represented the Cigale, or Cicada, under the form of a magnificent apple-green grasshopper. The artist materialised here, as we may say, the common mistake of the inhabitants of the north, which makes them confound the Cicada with the great green grasshopper.
For the rest, we may, by-the-by, say that La Fontaine’s fable of “La Cigale et la Fourmi” is full of errors in natural history. Nothing is easier than to prove the truth of this assertion. From the very first verses, the author shows that he has never observed the animal of which he speaks.
“La Cigale ayant chanté
Tout l’été.”
No Cicada could sing “tout l’été,” since it lives at the utmost for a few weeks only.
“Se trouva fort dépourvue
Quand la bise fut venue.”
“Quand la bise fut venue” means without doubt the month of November or December. But at this season of the year the Cicada has a long time since passed from life to death. When one wanders along the outskirts of woods as early as the month of October, in the south of France, one finds the soil covered with dead Cicadas. La Fontaine’s Cigale then could not have found itself “fort dépourvue,” for the simple reason that it was already dead.
“Elle alla crier famine
Chez la Fourmi, sa voisine,
La priant de lui preter
Quelque grain pour subsister.”
The ant is carnivorous, and although it likes honey, it has nothing to do with grains of wheat, nor with any other grain, of which, according to the fabulist, it had laid up a stock. On the other hand, the Cicada, which he blames for having
“Pas un seul petit morceau
De mouche ou de vermisseau,”
never dreamt of such victuals, for it lives entirely on the sap of large vegetables. The fables of the poet, who is called in France, one never knows why, “Le bon La Fontaine,” teem with errors of the same kind as those we have just pointed out. The habits of animals are nearly always represented as exactly the contrary to what they really are. To initiate himself into the mysteries of the habits of animals, La Fontaine certainly had neither the works of Buffon nor the memoirs of Réaumur, which had not then been written; but had he not the book of Nature?
But it is time to mention the principal species of the Cicada. We will describe two: that of the Ash, which lives on those trees in the south of France; and that of the Manna Ash, which is very common in the south-east of France. It is particularly plentiful in the forests of pines which abound between Bayonne and Bordeaux. It is on these two species of Cicada that Réaumur made the beautiful observations of which we gave a summary above.
The Cicada plebeia or Tettigonia fraxini, very common in Provence, is found, though rarely, in the forest of Fontainebleau, occasionally in La Brie. It is of a grey yellow below, black above; the head and thorax are marked or striped with black.
M. Solier, in a Memoir inserted in the “Annales de la Société Entomologique de France,” says that its song, very loud and very piercing, seems to consist of one single note, repeated with rapidity, which insensibly grows weaker after a certain time, and terminates in a kind of whistle, which can be partly imitated by pronouncing the two consonants st, and which resembles the noise of the air coming out of a little opening in a compressed bladder. When the Cicada sings, it moves its abdomen violently, in such a manner as alternately to move it away from, and to bring it near to, the little covers of the sonorous cavities; to this movement is added a slight trembling of the mesothorax.
The same entomologist relates a very interesting observation made on this species of Cicada by his friend, M. Boyer, a chemist at Aix, and which he himself verified. The Cicadas, in general, are very timid, and fly away at the least noise. However, when a Cicada is singing, one can approach it, whistling the while in a quavering manner, and imitating as nearly as possible, its cry, but in such a manner as to predominate over it. The insect then descends a small space down the tree, as if to approach the whistler; then it stops. But if one presents a stick to it, continuing to whistle, the Cicada settles on it and begins again to descend backwards. From time to time it stops, as if to listen. At last, attracted, and, as it were, fascinated by the harmony of the whistle, it comes to the observer himself.
M. Boyer managed thus to make a Cicada, which continued to sing as long as he whistled in harmony with it, settle on his nose. Charmed by this concert, the insect seemed to have lost its natural timidity.
The Cicada orni is of a greenish yellow, spotted with black. The abdomen is encircled by the same colours. The elytra and the wings are hyaline, or glassy, and their veins alternately yellow and brown. The legs are yellow throughout. The song of this species is hoarse, and cannot be heard at any great distance.
M. Solier, in the work we quoted just now, says that the song of this Cicada is of a deeper intonation, but that it is quick and is sooner over. It does not terminate in the manner which characterises that of the other species.
Next the genus Cicada comes Fulgora, whose type is the Fulgora lanternaria, or Lantern Fly (Fig. 83).
Belonging to South America, these insects are above all remarkable and easy to recognise, by their very large elongated head, which nearly equals three-quarters of the rest of the body. This prolongation is horizontal, vesiculous, enlarged to about the same breadth as the head, and presents above a very great gibbosity. The antennæ are short, with a globular second articulation, and a small terminal hair. The species represented in Fig. 83 is yellow varied with black. The elytra are of a greenish yellow, sprinkled with black; the wings, of the same colour, have at the extremity a large spot resembling an eye, which is surrounded by a brown circle very broad in front. It inhabits Guyana. This remarkable insect enjoys a great renown with the vulgar, by a peculiarity which might be called its speciality—the property of shining by night or in the dark. Hence its name of Fulgora lanternaria.
The knowledge of the Fulgora lanternaria has been spread and popularised in Europe by a celebrated book, which has for its title, “Métamorphoses des Insectes de Surinam.” This book, which contains the result of patient study of the natural history of Dutch Guyana (Government of Surinam), was written and published in three languages, by a woman whose name this work has rendered immortal—Mlle. Sybille de Mérian—and who won the admiration and respect of her contemporaries by her love of the beauties of Nature, and her perseverance in making them known and admired. Sybille de Mérian was born at Bâle. Daughter, sister, and mother of celebrated engravers, herself an excellent flower-painter, she had worked a long time at Frankfort and at Nuremburg; and had read with the greatest attention the “Théologie des Insectes,” 25 and with admiration Malpighi’sbook on the silkworm. Full of enthusiasm for the study ofnatural history, she left Germany, to visit the magnificent collectionof plants which were kept in the hot-houses of Holland, and madeadmirable reproductions of them with her pencil.
This attentive study of the vegetable world suggested to her the idea, which soon became an ardent desire, of observing these marvels of Nature in those parts of the globe in which they display themselves with the greatest magnificence and splendour. At the age of fifty-four, Sybille de Mérian set out for equatorial America. From the very first days of her arrival she hazarded her life, sometimes without a guide, in the swampy plains or burning valleys of Guyana. During the two years she sojourned in those dangerous parts, she made a large collection of drawings and paintings, which were destined to inaugurate in Europe the introduction of art into natural history.
In the plates to her work, Sybille de Mérian represents always the insects she wishes to describe under its three forms of larva, pupa, and perfect insect. With this drawing she gives another of the plants which serves the insect for food, as also of the animals which prey on it. Each plate is a little drama. Near the insect is seen the greedy lizard opening its dreadful mouth, or the ferocious spider watching for it. The short life of insects is shown here in its entirety, with its continual struggles, its infinite artifices, its rapid end, and all the episodes of its existence, for which life, as in the case of the moral man, is but a long and painful struggle.
Such was the work, such was the noble devotion and the worthy career of Sybille de Mérian. Let women, let young girls, who are martyrs to the ennui of a life devoid of occupation, peruse her beautiful books, and learn from it how much a woman may do with the time which is now either utterly unoccupied or only devoted to useless employments. To study Nature in any of its phases ought, it seems to us, to give more satisfaction to the soul, more strength to the mind, and cause more admiration of and gratitude to the supreme Author of Nature than doing a little embroidery.
It is, as we have already said, in the work of Sybille de Mérian, “Métamorphoses des Insectes de Surinam,” that one finds mentioned, for the first time, the luminous properties of the Fulgora lanternaria. The author thus relates her observations, which were the result of chance:—
“Some Indians having one day brought me a great number of the Lantern Flies, I shut them up in a large box, not knowing then that they gave light at night. Hearing a noise, I sprang out of bed and had a candle brought. I very soon discovered that the noise proceeded from the box, which I hurriedly opened; but, alarmed at seeing emerging from it a flame, or, to speak more correctly, as many flames as there were insects, I at first let it fall. Having recovered from my astonishment, or rather from my fright, I caught all my insects again, and admired this singular property of theirs.”
Since the time when Mlle. de Mérian visited Guyana, different travellers have said that they could not observe, as she did, this phosphorescent phenomenon. It is, then, probable that this property only exists in the male or female insect, and then only at certain seasons.
What a marvellous spectacle must the rich valleys of Guyana present, when, in the stillness of the night, the air is filled with living torches; when, the Fulgoræ flying about in space, the flashes of fire cross each other, go out and blaze up again, shine brightly and then die out, and present, on a calm evening, the appearance of those lightning flashes which are usually seen only in the midst of a tempest!
Let us now go on to another interesting insect of the order of which we are treating, the Aphrophora, without being frightened by its disagreeable name, for there are many other names we may give it if we choose among those by which it is popularly known. In the months of June and July one sees on nearly every tree, and on plants of the most different kinds, a sort of white froth, composed of air bubbles, deposited on the leaves and branches. It is produced by an insect which the peasants in France call Crachat de Coucou, or Ecume printanière (spring froth), and which is called in England, Cuckoo’s spittle. De Geer carefully studied the metamorphoses of this insect. The Aphrophora (from αφρος, foam, and φερω, I bear or carry) is lodged in the froth of which we have just been speaking. It lives in it, only leaving it when it has its wings. De Geer wondered why this insect confines itself during the whole of its life in liquid, and concludes that the froth has the effect of protecting the insect from the burning heat of the sun. This covering seems also to pro tect it from the attacks of carnivorous insects and spiders. On the other hand, its skin is without doubt so constituted that it would perspire too freely if it were exposed to the air, and the insect would very soon die dried up. Whatever explanation may be given of the necessity for this semi-aërial, semi-liquid medium, it is easy to verify the fact that the larva of the Aphrophora cannot live long out of its frothy envelope. If withdrawn from it, the volume of its body diminishes perceptibly, and the poor animal dies, like a fish taken out of its natural element.
The insects which live in this froth are six-legged grubs (Fig. 84), which, when the froth is cleared from them, walk quickly enough on the stalks and leaves of plants. They are green, with the belly yellow.
De Geer wished to know how they produced this singular froth, and found out in the following manner:—He took one of them out of its frothy dwelling, wiped it dry with a camel’s-hair pencil, and placed it on a young stalk, recently cut from the honeysuckle, which he put into water in a glass, in order to preserve its freshness, and this is what he observed:—
“It begins,” says the Swedish naturalist, “by fixing itself on a certain part of the stalk, in which it inserts the end of its trunk, and remains thus for a long time in the same attitude, occupied in sucking and filling itself with the sap. Having then withdrawn its trunk, it remains there, or else places itself on a leaf, where, after different reiterated movements of its abdomen, which it raises or lowers and turns on all sides, one may see coming out of the hinder part of its body a little ball of liquid, which it causes to slip along, bending it under its body. Beginning the same movements again, it is not long in producing a second globule of liquid, filled with air like the first, which it places side by side with, and close to, the preceding one, and continues the same operation as long as there remains any sap in its body. It is very soon covered with a number of small globules, which, coming out of its body one after the other, tend towards the front part, aided in this by the movement of the abdomen. It is all these globules collected together which form a white and extremely fine froth whose viscosity keeps the air shut up in the globules, and prevents its froth from easily evaporating. If the sap which the larva has drawn from the plant is exhausted before it feels itself sufficiently covered with froth, it begins to suck afresh, until it has got a new and sufficient quantity of froth, which it takes care to add to its first stock.”26
It is in the froth that the larvæ change into pupæ, and they do not leave their habitation to undergo their final metamorphosis. They have then, says De Geer, the art of causing the froth inside to evaporate and dry up, in such a manner as to form a space inside the mass of froth, in which their bodies are entirely free. The exterior froth forms a roof closed in on all sides, under which the insect lies quite dry.
In this vaulted cell the pupa disengages itself little by little from its skin, which first splits up along the head, and then on the thorax. This opening is sufficiently large to enable it to come out of its envelope. It is in the month of September that these insects are particularly abundant, and then the trees and plants are covered with them. Sometimes the froth drips off, like a sort of small rain, from branches which are covered with it. Towards the autumn the females are pregnant. They are then so heavy that they can hardly jump or fly. The males, on the contrary, make prodigious bounds; they throw themselves forward to a distance of more than two yards. They are very difficult to catch, and still more difficult to find again when one has once let them escape. And so Swammerdam calls these insects Sauterelles-Puces (Flea-Grasshoppers), because they jump like fleas.
All that we have said relates to the Aphrophora spumaria, or Froghopper (Fig. 85), an insect common all over Europe, and which Geoffroy calls the Cigale bedeaude.
“It is of a brown colour,” says Geoffroy, “often rather greenish. Its head, its thorax, and its elytra, are finely dotted; on these last one sees two white oblong spots. The lower part of the insect is light brown.” 27
We will mention, as it belongs to the group with which we are now occupied, a noxious insect, Iassus devastans, which since 1844 seems to have taken up its quarters in the commune of Saint Paul, in the department of the Basses-Alpes. It sucks the leaves and stalks of cereals, causing them to wither, and may be found even in winter on young corn, but principally in the spring. According to M. Guérin-Méneville, its head is of an ochrey yellow, with the apex marked with black spots; the forehead yellow, elongated, striped with black, as are the legs. The elytra are straw-coloured and spotted with brown. The wings are transparent, and slightly blackened at the extremities. This remarkable insect, which is not more than the twelfth of an inch in length, jumps and flies with great ease.
1. Hypsauchenia balista.
2. Membracis foliata. 3. Centrotus cornutus.
4. Umbonia Spinosa. 5. Bocydium globulare.
6. Cyphonia furcata.
A small brownish insect, whose strange appearance struck Geoffroy, the historian of the insects of the environs of Paris, may be seen springing over the fern stalks and thistles, in the damp parts of most of the woods of Europe.
Geoffroy calls this insect “le Petit Diable.” “Le Petit Diable,” he writes, “is of a dark blackish-brown. Its head is flat, projecting but slightly, and, as it were, bent downwards. Its thorax, which is rather broad, has two sharp horns, which terminate in pretty long points on the sides. In the middle of the thorax is a crest or comb, which, prolonged into a sort of sinuous and crooked horn, terminates in a very sharp point, reaching to within one quarter of the extremity of the wing-cases. These—viz., the wing-cases—are dark, with brown veins; and the wings, shorter than their cases, are rather transparent. The insect jumps very well, and is not readily caught.”28
The Petit Diable of Geoffroy is the Centrotus cornutus of modern naturalists. This curious little insect belongs to a strange and remarkable group, whose thorax takes the most extraordinary and most varied forms, as may be seen in Fig. 86, which represents somewhat magnified, many of these insects. Nearly all inhabit Guyana, the Brazils, and Florida.
We will now proceed to examine one of the most interesting groups of insects—that of the Plant-lice. These insects have for a long time attracted the attention of naturalists. They are so abundant that all our readers have seen them, and there are few plants in our fields or gardens which do not nourish some species. How often does one hesitate in gathering a rose or a bit of honeysuckle, for fear of touching the unattractive guest of those charming flowers!
During the whole of the summer one sees on the branches, on the leaves, but principally on the young shoots of the rose-tree, large companies of green plant-lice, which subsist on the sap of the tree. Some are provided with wings (Figs. 87, 88), others are wingless (Figs. 89, 90). The last-named are the largest, and are a line and a half long. They are entirely green, except two parts, of which we will speak immediately. The body is oval; the head is small, and furnished with two brown eyes. The skin is smooth, and tightly drawn over the body. The antennæ, which are very long and slender, almost equal the body in length. The six legs are long and slim, and the short feet terminate in two hooks. On the upper part of the body are two small cylindrical horns, surmounted by a small knob. The antennæ and these horns are black.
The winged individuals are of the same size as these, but are of a dark green colour, mixed with black. The wings are transparent, and the upper ones are as long again as the body. The young shoots of the elder-tree, all round their circumference for the length of from a foot to a foot and a half, are often covered with black plant-lice, or with those of a greenish-black colour. They are crowded one against the other, and sometimes there are two layers of them.
If observed without moving the plant about, they appear to be tranquil and inactive. They are, however, then absorbing from the plant the nourishment it should have; piercing with the point of their trunks the epidermis of the leaves or stalks, and drawing from them a nourishing liquid.
But this occupation is confined to those which are on the plant itself. Those which, on account of the enormous agglomeration of these insects, walk, not on the branch, but on other plant-lice, and cannot therefore suck the sap of the plant, are employed entirely in preserving and multiplying their species.
Réaumur often saw the latter, easily recognised by their great size, giving birth to little plant-lice, which are quite alive when they leave their mother. The young ones set off and mount or descend till they reach one end of the crowd, and there each takes up its position, like a cardboard capuchin (capucin de carte), in such a manner that the head is just behind the plant-louse which precedes it. There they bury their trunks in the vegetable tissue, and set to work to imbibe the sap.
Small as is the trunk of the plant-louse, yet when there are thousands of those little beings fixed to the stalk or the leaves of a plant, it is evident that it must suffer. And so the plant-louse is, in truth, one of the most terrible enemies of our agricultural and horticultural productions, and the exact list of the ravages which it occasions would be indeed interminable. We will confine ourselves to a few examples. For some years the lime-tree aphis has seriously attacked the lime-trees of the public promenades of Paris. The peach-tree plant-louse causes the blight of the leaves of that tree. It is to these prolific little parasites that are due, in a great number of cases, the contortions of leaves and of the young shoots of trees of all sorts.
These insatiable depredators cause sometimes a still more remarkable alteration. On the leaves of elms are often seen bladders round and rosy, like little apples. On opening these bladders one finds that they are inhabited by a species of aphis. On the black poplar galls of different kinds grow, some from the leaf stalks, and others from the young stems. They are rounded, oblong, horned, and twisted into a spiral. Other galls show themselves on the leaf itself. They are all inhabited by plant-lice, differing from those of which we have given a description above, in the extremity of their abdomen not presenting the two remarkable horns to which we shall have later to call the attention of the reader. The body is generally covered with a long and thick down.
Of this genus, the species, alas! so unfortunately celebrated is the Apple-tree Aphis (Myzoxyle mali), which attacks that tree. This insect is of a dark russet brown, with the upper part of the abdomen covered with very long white down. Its presence was announced for the first time in England in 1789, and in France, in the department of the Côtes du Nord, in 1812. In 1818 it was found in Paris, in the garden of the École de Pharmacie. It had become common in 1822 in the departments of the Seine, the Somme, and the Aisne. In 1827 its presence in Belgium was announced.
The apple-tree aphis, according to M. Blot, can only exist on that tree. Carried away and placed on any other, it very soon perishes. It does not attack the blossom, the fruit, nor the leaves, but fixes itself on the lower part of the trunk, whence it propagates itself downwards as far as the roots, underneath the graftings, &c. It also likes to lodge in cracks of the trunk and large branches. But it always looks out for a southern, and avoids a northern aspect. It is not active, walks very little, and its dissemination from one place to another can only be explained by the facility with which so small an insect can be transported by the wind, its lightness being still more increased by the down which covers it.
The Myzoxyle mali renders the wood knotty, dry, hard, brittle, and brings on rapidly all the symptoms which characterise old age and decay in attacked trees. M. Blot recommends the following means for preserving the apple-tree from this insect: Employ for the seed-beds the pips of bitter apples only; give to the nursery and to the plants only as much shelter as is absolutely necessary; avoid those sites which are too low and too damp; encourage the circulation of air, and the desiccation of the soil; surround the foot of each apple-tree with a mixture of soot or of tobacco and fine sand.
As for the manner of freeing a tree once invaded by this insect, the most simple plan is to rub the trunk and the branches, in order to crush the insects, or to employ a brush or broom.
We spoke above of the reproduction of the aphis, but without entering into any particular details; we will now touch upon this question, one of the most interesting in natural history.
It was at the time when Réaumur was writing his immortal “Histoire des Insectes,” when Trembley was publishing his admirable researches on the freshwater Hydra, whose wonderful vitality we have mentioned in our work on Zoophytes and Molluscs,29 that another naturalist astonished the learned world by his experiments on the reproductions of plant-lice. This naturalist, whose name will live quite as long as those of Réaumur and of Trembley, was Charles Bonnet, of Geneva.
Charles Bonnet made the extraordinary discovery that aphides can increase and multiply without the intervention of the sexes. An isolated specimen can produce a series of generations of its kind. We will relate the curious experiments of the Genevese naturalist. He placed in a flower-pot, filled with mould, a phial full of water, and put into this phial a little branch of spindle, having only five or six leaves, and perfectly free from any insect. On one of these leaves he placed a plant-louse, which was born under his own eyes, of a wingless mother. He then covered the branch with a glass shade, whose rim fitted exactly into the top of the flower-pot. Having taken these precautions, Charles Bonnet was perfectly certain of being able to observe his prisoner at his ease. He could keep it under his eye and under his hand, with more certitude and security than was the mythological Danaë, shut up, by order of Acrisius, in a tower of bronze.
“I took care,” says Charles Bonnet, “to keep a correct journal of the life of my insect. I noted down its least movements; nothing it did seemed to me indifferent. Not only did I observe it every day from hour to hour, beginning generally at four or five o’clock in the morning, and only leaving off at about nine or ten at night; but I even looked many times in the same hour, and always with the magnifying glass, to render my observation more exact, and to learn the most secret actions of my little lonely one. But if this continual application cost me some trouble, and bored me not a little, in amends I had some cause for self-applause and for having subjected myself to all this trouble.... My plant-louse changed its skin four times: on the 23rd, in the evening; on the 26th, at two in the afternoon; on the 29th, at seven o’clock in the morning; and on the 31st, at about seven o’clock in the evening.... Happily delivered from these four illnesses through which it was obliged to pass, it at last reached that point to which, by my care, I had been trying to bring it. It had become a perfect plant-louse. On the 1st of June, at about seven o’clock in the evening, I saw, with great satisfaction, that it had given birth to another; from that time I thought I ought to look upon it as a female. From that day up to the 20th inclusive, she produced ninety-five little ones, all alive and doing well, the greatest number of which were born under my own eyes!” 30
He very soon made some other experiments on the aphis of the elder-tree, so as to assure himself if the generations of plant-lice, reared successively in solitude, preserved the same property of procreating without copulation.
“On the 12th of July,” says he, “about three o’clock in the afternoon, I shut up a plant-louse that had just been born under my eyes. On the 20th of the same month, at six o’clock in the morning, it had already produced three little ones. But I waited till the 22nd towards noon before I shut up a plant-louse of the second generation, because I could not manage earlier to be present at the birth of one of those produced by the mother I had condemned to live in solitude. I always continued to observe the same precaution. I shut up only those plant-lice which were born under my very eyes. A third generation began on the 1st of August; it was on this day that the plant-louse I had shut up on the 22nd of July gave birth to this generation. On the 4th of August, about one o’clock in the afternoon, I put into solitary confinement a plant-louse of the third generation. On the ninth of the same month, at six in the evening, a fourth generation, due to this last one, had already seen the light: it had given birth to four little ones. On the same day, towards midnight, all intercourse with its own species was forbidden to the plant-louse of the fourth generation born at that hour. On the 18th, between six and seven o’clock in the morning, I found this last in the company of four little ones to which it had given birth.”31
In this case, the want of food caused the death of the isolated individual of the fifth generation, and the experiment was brought to a close.
Bonnet then tried experiments on the plantain aphis, following them up during five consecutive generations, which succeeded each other without interruption, in the space of three months.
After having stated the extraordinary facts, which he relates with the most perfect simplicity, Charles Bonnet, examining at the end of the fine season specimens of the winged oak-tree aphis, was able to be present at their nuptials. He preserved the females with great care, and saw, not without profound astonishment, that they gave birth, not to small living insects, as was the case in the first experiments, but to eggs of a reddish colour, which were stuck fast to each other, on the stem or stalk of the plant.
A short time afterwards, this illustrious observer was able to convince himself that the oak-tree plant-lice, whose nuptials he had witnessed in the autumn, present the same phenomena of solitary and viviparous propagation, already so often mentioned by him.
At last some new observations permitted him to establish beyond all doubt the connection of these facts, in appearance so contradictory. He discovered that, during the whole of the fine season, the plant-lice are solitary and viviparous, but that towards the autumn these creatures return to the ordinary course of things, and are propagated by eggs, whose development requires the co-operation of a male and female individual. These eggs are hatched in Spring, and produce only viviparous plant-lice. In the autumn the males and females show themselves, and from that moment ovipositing recommences. These curious facts, seen and published more than a century ago, have been verified many times since. In 1866 M. Balbiani asserted that the plant-lice are hermaphrodite, or of both sexes at the same time, which would explain the facts observed by Charles Bonnet. But the anatomical proofs appealed to by Balbiani in support of this idea are far from establishing the existence of this arrangement of sexes among them. The observations of Charles Bonnet produced profound astonishment among naturalists, and, in this respect, 1743 may be considered as a memorable year.
The simple statement of the few experiments which he made, and which we have cited, has sufficed to show how rapid is the multiplication of aphides. A single female produced generally 90 young ones; at the second generation these 90 produce 8,100; these give a third generation, which amounts to 729,000 insects; these, in their turn, become 65,610,000; the fifth generation, consisting of 590,490,000, will yield a progeny of 53,142,100,000; at the seventh, we shall thus have 4,782,789,000,000; and the eighth will give 441,461,010,000,000. This immense number increases immeasurably when there are eleven generations in the space of a year. Fortunately a great many carnivorous insects wage fierce war against the plant-lice, and destroy immense numbers of them. Thus they are kept in check, and prevented from multiplying inordinately. To show with what prodigious abundance the reproduction of these little but formidable parasites must go on, we will relate a fact which was made known to us by M. Morren, Professor in the University of Liége.
The winter of 1833-34 had been extremely warm and dry; whole months had passed without any rain. A well-known savant, Van Mons, had foretold, as early as the 12th of May, that all the vegetables would be devoured by plant-lice. On the 28th of September, 1834, at the moment when the cholera had began to spread its ravages over Belgium, all of a sudden a swarm of plant-lice showed themselves between Bruges and Ghent. They were to be seen the next day at Ghent, hovering about in troops, in such quantities that the daylight was obscured. Standing on the ramparts, one could no longer distinguish the walls of the houses in the town, so covered were they with plant-lice. The whole road from Antwerp to Ghent was rendered black by innumerable legions of them. They appeared everywhere quite suddenly. People were obliged to protect their eyes with spectacles and their faces with handkerchiefs, to keep off the painful and disagreeable tickling caused by them. The progress of these insects was interrupted by mountains, hills, even by undulations of land of very slight elevation, but sufficient to have an influence on the wind. M. Morren thinks that they came from a great distance, and that they arrived in Belgium by the sea-coast. Whatever be the explanation of the phenomenon, it establishes sufficiently the prodigious multiplication of these little insects.
There is another trait, and without doubt the most curious in the history of the aphides, to which we have still to call the attention of the reader: we mean the relations which exist between them and the ants.
No one can have failed to observe ants frequenting those places where plant-lice are gathered together in great numbers. Are ants simply friends of the plant-lice, as thought the ancients? or have their visits some selfish object?
Linnæus, Bonnet, and Pierre Huber thought that the ants did not pay these visits for nothing, and that they had some object in view. But what could they want of the plant-lice? It is to Pierre Huber we owe the solution of this mystery. This naturalist has made the most beautiful observations on the relations which exist between plant-lice and ants. They are detailed in a chapter of his admirable work, entitled “Recherches sur les Mœurs des Fourmis Indigènes.”
The plant-lice have, as we have said, at the extremity of their abdomen, two small movable horns. These are in communication with a little gland which produces a sugary liquid. When one carefully observes plant-lice attached to the stem of a plant, one sees a little syrup droplet oozing out of the extremity of these tubes.
M. Morren, who has made some interesting observations on the anatomy and generation of the aphis, says that, having shut up females in wide-mouthed glass bottles, he saw the young, a little time after their birth, suck the sweet juice which exudes from the little tubes at the extremity of the mother’s abdomen. This secretion seems, then, destined for the nourishment of the young in the first moments of their existence, before they are able to nourish themselves on vegetable juices. The saccharine fluid produced by the mother must be, then, a sort of milk intended for the nourishment of her young. This being settled, attend to what follows. In all places where plant-lice are assembled in great numbers it is easy to observe how excessively fond ants are of the sugary liquid destined for suckling the young. But how do the ants manage to get the plant-lice to allow themselves to be, as we may say, milked?
“It had been already noticed,” says this celebrated observer, “that the ants waited for the moment at which the plant-lice caused this precious manna to come out of their abdomen, which they immediately seized. But I discovered that this was the least of their talents, and that they also knew how to manage to be served with this liquid at will. This is their secret. A branch of a thistle was covered with brown ants and plant-lice. I observed the latter for some time, so as to discover, if possible, the moment when they caused this secretion to issue from their bodies; but I remarked that it very rarely came out of its own accord, and that the plant-lice, which were at some distance from the ants, squirted it out with a movement resembling a kick.
“How did it happen, then, that the ants wandering about on the thistle were nearly all remarkable for the size of their abdomens, and were evidently full of some liquid? This I discovered by narrowly watching one ant, whose proceedings I am going to describe minutely. I saw it at first passing, without stopping, over some plant-lice, which did not seem in the least disturbed by its walking over them; but it soon stopped close to one of the smallest, which it seemed to coax with its antennæ, touching the extremity of its abdomen very rapidly, first with one of its antennæ and then with the other. I saw with surprise the liquid come out of the body of the plant-louse, and the ant forthwith seize upon the droplet and convey it to its mouth. It then brought its antennæ to bear upon another plant-louse, much larger than the first; this one, caressed in the same manner, yielded the nourishing fluid from its body in a much larger dose. The ant advanced and took possession of it. It then passed to a third, which it cajoled as it had the preceding ones, giving it many little strokes with its antennæ near the hinder extremity of its body; the liquid came out immediately, and the ant picked it up.... A small number of these repasts are sufficient to satisfy the ant’s appetite. (See Fig. 91.)
“It does not appear that it is out of importunity that these insects obtain their nourishment from the plant-lice.
“The neighbourhood of ants is agreeable to plant-lice, since those which could get out of the way of their visits, viz., the winged plant-lice, prefer to remain amongst them, and to lavish upon them the superabundance of their nourishment.”32
What we have just related applies not only to the brown (Formica brunnea), but also to the tawny ant (Formica flava), to the ashy black (Formica nigra), to the fuliginous (Formica fuliginosa), and to a great many more.
The Red Ant (Formica rufa) is singularly adroit in seizing the droplet left it by the plant-louse. According to Pierre Huber, it employs its antennæ, which swell somewhat towards their extremities, in conveying this droplet to its mouth, and causes it to enter it by pressing it first on one side, then on the other, using its antennæ as if they were fingers. The greater number of ants seek them on those plants on which they usually fix themselves—the lowest herbs, as well as the highest trees. There are some, however, which never leave their place of abode, and never go out to the chase. These are the little ants, of a pale yellow colour, rather transparent, and covered with hairs, and which are extremely numerous in our meadows and orchards. These subterranean creatures are very noxious to the farmer. Pierre Huber often wondered how they subsisted, and with what food they could provision themselves, without quitting their gloomy habitations. Having one day turned up the earth of which a habitation was composed, in order to discover if any treasure were to be found stowed away there, he found nothing but plant-lice. Of these the greater number were fixed to the roots of the trees which hung down from the roof of their subterranean nest; others were wandering about among the ants. These latter, moreover, set about milking their nurses, as usual, and with the same success. To verify his discovery, he dug up a great number of nests of the yellow ant, and invariably found aphides in them. So as to study the relations which must exist between these insects, he shut up ants with their friends, the plant-lice, in a glazed box, placing at the bottom of the box, earth, mixed with the roots of some plants, whose branches vegetated outside the box. He watered this ant-hill from time to time, and thus both the animals and the plants found in his apparatus sufficient nourishment.
“The ants,” he says, “did not endeavour in the least to make their escape. They seemed to want for nothing, and to be quite content. They tended their larvæ and females with the same affection they would have shown in their usual ant-hill; they took great care of the plant-lice, and never did them any harm. These, on the other hand, did not seem to fear the ants; they allowed themselves to be moved about from one place to another, and when they were set down they remained in the place chosen for them by their guardians. When the ants wished to move them to a fresh place, they began by caressing them with their antennæ, as if to request them to abandon their roots or to withdraw their trunk from the cavity in which it was inserted; then they took them gently above or below the abdomen with their jaws, and carried them with the same care they would have bestowed on the larvæ of their own species. I saw the same ant take three plant-lice in succession, each bigger than itself, and carry them away into a dark place.... However, the ants do not always act so gently towards them. When they fear that they may be carried off by ants of another kind, and living near their habitation, or when one opens up too suddenly the turf under which they are hidden, they seize them up in haste and carry them off to the bottom of their little cavern. I have seen the ants of two different ant-hills fighting for their plant-lice. When those belonging to one ants’ nest could enter the nest of the others, they took them away from their rightful owners, and often these took possession of them again in their turn; for the ants know well the value of these little animals, which seem made on purpose for them,—they are the ants’ treasures. An ants’ nest is more or less rich, according as it is more or less stocked with plant-lice. The plant-lice are its cattle, its cows, its goats. One would never have thought that the ants were a pastoral people!”33
Their hiding in the ants’ nest is not voluntary; they are prisoners of war. The ants, after having hollowed out galleries in the midst of roots, make a foray upon the turf, and seize upon plant-lice scattered about here and there, bringing them with them, and collect them together in their nests. The captive insects take their wrongs with patience, and behave like philosophers under this new kind of life. They lavish on their masters, with the best grace in the world, the nutritious juices with which their bodies superabound. Charles Bonnet has stated some real wonders of the cleverness and industry of other ants which also make a provision of plant-lice.
“I discovered one day,” says he, “a Euphorbia, which supported in the middle of its stem a small sphere, to which it served as the axis. It was a case which the ants had constructed of earth. They issued forth from this by a very narrow opening made in its base, descended the stem, and passed into a neighbouring ants’ nest. I destroyed one part of this pavilion, built almost in the air, so that I might study the interior. It was a little room, the vault-shaped walls of which were smooth and even. The ants had profited by the form of the plant to sustain their edifice. The stalk passed up the centre of the apartment, and for its timber-work it had the leaves. This retreat contained a numerous family of plant-lice, to which the brown ants came peacefully, to make their harvest, sheltered from the rain, the sun, and from other ants. No insect could disturb them; and the plant-lice were not exposed to the attacks of their numerous enemies. I admired this trait of industry; and I was not long in finding it again, in a more interesting character, in ants of different species.
“Some red ants had built round the foot of a thistle a tube of earth, two inches and a half long by one and a half broad. The ants’ nest was below, and communicated directly with the cylinder. I took the stalk, with what surrounded it, and all that the cylinder contained. That portion of the stem which was inside the earthen tube was covered with plant-lice. I very soon saw the ants coming out at the opening I had made at the base; they were very much astonished to see daylight at that place, and I saw that they lived there with their larvæ. They carried these with great haste to the highest part of the cylinder which had not been altered. In this retreat they were within reach of their plant-lice, and here they fed their young.
“In other places many stalks of the Euphorbia laden with plant-lice rose in the very centre of an ant-hill belonging to the brown ants. These insects, profiting by the peculiar arrangement of the leaves of this plant, had constructed round each branch as many little elongated cases; and it was here they came to get their food. Having destroyed one of these cells, the ants forthwith carried off into their nests their precious animals; a few days afterwards it was repaired under my eyes by these insects, and the herd were taken back to their pens.
“These cases are not always at a few inches from the ground. I saw one five feet above the soil, and this one deserves also to be described. It consisted of a blackish, rather short tube, which was built round a small branch of the poplar at the point where it left the trunk. The ants reached it by the interior of the tree, which was excavated, and without showing themselves, they were able to reach their plant-lice by an opening which they had made in the base of this branch. This tube was formed of rotten wood, of the vegetable earth of this very tree, and I saw many a time the ants bringing little bits in their mouths to repair the breaches I had made in their pavilion. These are not very common traits, and are not of the number of those which can be attributed to an habitual routine.” 34
One day, Pierre Huber discovered in a nest of yellow ants a cell containing a mass of eggs having the appearance of ebony. They were surrounded by a number of ants, which appeared to be guarding them, and endeavouring to carry them off.
Huber took possession of the cell, its inhabitants, and of the little treasure it contained, and placed the whole in a box lid, covered with a piece of glass, so as to be more easily observed. He saw the ants approach the eggs, pass their tongues in between them, depositing on them a liquid. They seemed to treat these eggs exactly as they would have treated those of their own species; they felt them with their antennæ, gathered them together, raised them frequently to their mouths, and did not leave them for an instant. They took them up, and turned them over, and after having examined them with care, they carried them with extreme delicacy into the little box of earth placed near them. 35
These were not, however, ants’ eggs. They were the eggs of aphides. The young which were soon to be hatched were to give to the provident ants a reward for the attentions they had lavished upon them. How wonderful are the life and the habits of the plant-lice, and their relations to ants! But we should be led on too far, if we were to pursue these attractive details.
We pass on now to the history of another family—namely, the Gallinsecta, as Réaumur calls them, or Cocci. They pass the greatest part of their lives—that is to say, many months—entirely motionless, sticking to the stalks or branches of shrubs; remaining thus as devoid of movement as the plant to which they are attached. One would say that they were part and parcel of it. Their form is so simple, that nothing in their exterior would make one guess them to be insects. The larger they become the less they resemble living things. When the coccus is in a state for multiplying its species, when it is engaged in laying its thousands of eggs, it resembles only an excrescence of the tree.
The Gallinsecta are found on the elm, the oak, the lime, the alder, the holly, the orange-tree, and the oleander. Some of the species are remarkable for the beautiful red colouring matter which they furnish. Such are the Coccus cacti, the Chermes variegatus, or Oak Tree Cochineal, and the Coccus polonicus.
The Common Cochineal, Coccus cacti, is found in Mexico, on the Nopal, or prickly pear (Opuntia), particularly on the Opuntia vulgaris, the Opuntia coccifera, and the Opuntia una, plants which belong to the family of the Cactaceæ.
These insects are rather remarkable, in that the male and female are so unlike, that one would take them for animals of different genera.
The male presents an elongated, depressed body, of a dark-brown red. Its head small, furnished with two long feathery antennæ, has only a rudimentary beak. The abdomen is terminated by two fine hairs, longer than its body. The wings, perfectly transparent, reach beyond the extremity of its abdomen, and cross each other horizontally over its back. It is lively and active. The female presents quite a different appearance. It is in the first place twice as large as the male (Fig. 92), convex above, flat below. It resembles a larva, and has no wings. Its body is formed of a dozen segments, covered with a glaucous dust. The beak is very fully developed, and the two hairs or bristles on the abdomen are much shorter than in the male.
The weight of the body, combined with the shortness of the legs, prevents these creatures from being active. The legs only serve, in fact, for clinging to the vegetable from which they draw their nourishment. The circumstances attending the birth of the cochineal insect are very curious. The larvæ are born in the dried-up body of their dead mother, the skeleton of their mother serving them as a cradle. This happens thus:—The eggs are attached to the lower part of the mother’s body. When the abdomen of the mother is empty, its lower side draws up towards the upper side, and the two together form a pretty large cavity. When the mother dies, which is not long in happening, her abdomen dries up, her skin becomes horny, and forms a sort of shell. It is in this membranous cradle that the larvæ of the cochineal insect are born. The cochineal insect in its wild state lives in the woods. But it can without difficulty be reared artificially.
Every one knows that the little insect called the cochineal, furnishes, when its body has been dried and reduced to powder, a colouring matter of a beautiful red, peculiar to itself. This circumstance has saved the cochineal from the persecution to which so many other kinds of insects have been devoted by the hand of man. In hot climates, in which the cochineal insect delights, it has been preserved, and is cultivated as an article of commerce. This is how the cochineal is reared in Mexico:—An open piece of land is chosen, protected against the west wind, and of about one or two acres in extent. This is surrounded with a hedge of reeds, planted in lines, distant from each other about a yard, with cuttings of cactus at most about two feet apart. The cactus garden made, the next thing is to establish in it cochineals. With this object in view they are sought in the woods, or else the females of the cochineal insect which are pregnant are taken off plants which have been sheltered during the winter, and placed in dozens, in nests made of cocoa-nut fibres, or in little plaited baskets made of the leaves of the dwarf palm, and hung on the prickles of the cactus. These are very soon covered with young larvæ. The only thing now required to be done is to shelter them from wind and rain. (Plate IV.)
The larvæ are changed into perfect insects, which take up their abode permanently on the branches of the cacti, as Fig. 93 represents. The Mexicans gather them as soon as they have reached the perfect state. The harvest cannot be difficult, considering the immobility of these little creatures. When collected, the cochineals are killed, packed in wooden boxes, and sent to Europe, to be used in dyeing.
Such is the method, very simple, as we see, of rearing the cochineal—a method which has been followed for centuries in Mexico. Towards the end of the year 1700, a Frenchman named Thierry de Menouville, formed the project of taking this precious insect away from the Spaniards, and of bestowing it upon the French colonies. He landed in Mexico, and concealed so well the object of his voyage, that he managed to embark and carry to St. Domingo several cases containing plants covered with living cochineals. Unfortunately, a revolution which had broken out at St. Domingo prevented him from succeeding in his praiseworthy endeavours. The cochineals died, and the Spaniards preserved their monopoly in the rearing of this insect.
In 1806 M. Souceylier, a surgeon in the French navy, succeeded in bringing from Mexico into Europe some live cochineals. He gave them to the professor of botany at Toulon; but this attempt to preserve them was unsuccessful.
In 1827 the naturalisation of the cochineal was attempted in Corsica, but without success. During the same year the cochineal was introduced into the Canary Islands, but the inhabitants did not understand the importance of the experiment. They counted the cochineal among the number of noxious insects, and tried in all ways to rid themselves of it. It was only after results obtained by some more intelligent farmers, that the inhabitants of the Canary Islands perceived the profits they might derive. From that time its cultivation was extended, and after the year 1831 it increased rapidly. Thus, the cochineal imported from the Canary Isles in that year amounted to only 4 kilogrammes. In 1832 the amount was 60 kilogrammes, in 1833 it was 660 kilogrammes, in 1838, 9,000 kilogrammes, and in 1850, 400,000 kilogrammes. The French colonists in Algeria also tried to raise it. In 1831, M. Limonnet, a chemist of Algiers, collected some cochineals, and had the merit of first introducing the insect into the colony. On account of bad weather these first essays were fruitless, but it was not long before they were repeated.
M. Loze, surgeon in the navy, undertook to introduce the insect again, and, with M. Hardy, director of the central garden of Algiers, gave himself up, with great intelligence, to the naturalisation and rearing of the cochineal in Algeria.
In 1847 the French Minister of War, for the purpose of having the value of the Algerian cochineal fixed by commerce, caused to be sold publicly on the market-place of Marseilles a case of cochineal, the produce of the harvests of 1845 and 1846, from the experimental garden of Algiers, and which contained 17 kilogrammes of this commodity. Since that time the cultivation of this insect, the beginning of which was due to M. Limonnet, has rapidly developed. In 1853, in the province of Algiers alone, there were fourteen nopaleries, or cactus gardens, containing 61,500 plants. The Government at that time bought the harvests for fifteen francs the kilogramme.
We have only pointed out in a general way how the cochineal harvest is conducted. We will now enter into some details on the subject. These insects are gathered when the females are about to lay, that is, when a few young are hatched. It is when the females are pregnant that they contain the greatest amount of colouring matter. When the harvest time has arrived, the rearers stretch out on the ground pieces of linen at the foot of the plants, and detach the cochineals from them, brushing the plants with a rather hard brush, or scraping them off with the blade of a blunt knife.
If the season is favourable, the operation may be repeated three times in the course of a year in the same plantation. The insects thus collected are killed, by dipping into boiling water, by being put into an oven, or by being placed on a plate of hot iron. The cochineals, when withdrawn from the boiling water, are placed upon drainers, first in the sun, then in the shade, then in an airy place. During their immersion in water they lose the white powder which covers them. In this state they are called in Mexico ronagridas. Those which have passed through the oven they call jaspeadas, and are of an ashy grey; those that are torrefied are black, and are called negras. In commerce three sorts of cochineal are recognised; first, the mastique (mestèque), of a reddish colour, with a more or less abundant glaucous powder; secondly, the noire, which is large and of a blackish brown; thirdly, the sylvestre, which is, on the contrary, smaller and reddish. The latter is the least esteemed, and is gathered on wild cacti.
Each year there are imported into France 200,000 kilogrammes of cochineals, which represents a value of about three millions of francs. Every one knows that it is from cochineal that carmine is made, a magnificent red frequently employed by painters. Lake carmine is another product obtained from the cochineal. And, lastly, scarlet is the powder of the cochineal precipitated by a salt of tin.
Before the Mexican cochineal was known in Europe, the kermes, or Coccus ilicis, known still in commerce and by chemists under the names of Animal kermes, Vegetable kermes, and Scarlet seed, was used for the preparation of the carmine employed in the arts. This cochineal lives by preference (at least, so it is supposed) on the evergreen oak (Quercus ilex), whence its specific name.
The Coccus ilicis develops itself almost exclusively, not on the evergreen oak, but on the Quercus coccifera, or kermes oak, a shrub common in dry arid places on the Continent, and which vegetates on a great number of spots in the Mediterranean, particularly on the garrigues, or waste land, of Herault.
The females of this insect, which, dried, bear the name of graines de kermes, are of the size of an ordinary currant, without any trace of rings, nearly spherical, of a violet and glaucous colour. They adhere to the boughs of the shrub Quercus coccifera, and form dry brittle masses, which the peasants of the south of France collect, and sell at a tolerably high price.
Before we possessed the cochineal of Mexico and of Algeria, this cochineal was very much employed in the south of Europe, in the East, and in Africa. It furnishes a beautiful red colour. This last named and the Mexican cochineal are somewhat used in pharmacy. They enter into alkermes, a sort of liquor served at dinner in Italy, chiefly at Florence and Naples.
Another species of cochineal is the Coccus polonicus, which is met with in Poland and Russia, more rarely in France, on the roots of a small plant, the Scleranthus perennis. This cochineal is gathered in the Ukraine towards the end of June, when the abdomen of the female is swollen, and filled with a purple and sanguineous juice.
The Polish kermes (Coccus polonicus) was formerly used very much in Europe. This product has not indeed lost all its importance in those countries where it is met with in abundance.
We have now only to point out among the insects of this group the Coccus lacca, which lives in India on many trees, among others on the Indian fig-tree, the Pagoda fig-tree, the Jujube tree, on the Croton, &c.
These last-mentioned insects produce a colouring matter known under the name of Lac Dye. They fix themselves on the little branches, getting together in great numbers, forming nearly straight lines. The bodies of many fecundated females, united together by a resinous exudation which is caused by the piercing of the bark, constitutes the matter called in commerce and by dyers by the name of Lac Dye, Shell-lac, Gum-lac, &c.
Resinous lac is found in commerce under four forms:—First, the stick-lac, such as it is found concreted at the extremity of the branches whence it exudes—it is an irregular brownish crust; secondly, the seed-lac, picked off the branches and pounded; thirdly, shell-lac in scales melted down and run into thin plates, which vary in quality according to the proportion of colouring matter they contain; fourthly, thread-lac, which resembles reddish threads, and is prepared thus in India.
One more word about the cochineal. The Coccus manniparus, which lives on the shrubs (Tamarix mannifera) on Mount Sinai, causes to exude from the branches it has pierced a sort of manna. The Coccus sinensis produces a kind of wax which is employed in China in the manufacture of candles.