The Silver-spotted Skipper (Augiades Comma)
This butterfly is very similar on the upper side to the Large Skipper, but the spots, especially those nearest the front edge of the fore wings, are yellower. On the under side the greenish tinge of the ground colour, and the silvery spots, make the identification quite easy. The black sex mark in the male is very similar to that of the last species (Plate 126).
The males vary a little in the width of the marginal border, and in some females there is almost as much fulvous on the discal area of the wings as in the male; in the darkest females the spots always appear paler than in fulvous specimens. On the under side the ground colour is sometimes olive-brown rather than green.
The following account of the life-history of this butterfly is adapted from Mr. Frohawk’s article on the subject published in the Entomologist for 1901:—
In August, whilst watching some of the butterflies on the wing over a patch of chalky ground covered with a short dense growth of various grasses, etc., he noted a female hovering close over the plants. Presently it settled on a tuft of hair grass (Aira cæspitosa), and after walking over and among it a little time, she curved her abdomen down, and deposited a single egg on one of the fine hair-like blades, or, rather, spines, and close by, within an inch, another egg was found. Afterwards some plants of this grass were potted up, and some females placed on them. These deposited a large number of eggs upon the grass-stems and blades.
The egg when newly laid is pearl white with the slightest yellowish-green tinge, which very gradually turns deeper in colour, assuming a pale straw-yellow on the sixth day, and so it remains until January, when it becomes paler.
The caterpillar hatches out at the end of March or early in April. It does not eat the empty egg-shell, but directly after leaving the egg it starts spinning the fine grass together into a somewhat dense cluster an inch or two above the ground. In this compact shelter the larva lives and feeds upon the grass surrounding it, remaining almost always completely hidden. Sometimes as many as three or four live together. When full grown and about one hundred days old, the caterpillar is of a dull olive-green colour, with a black collar on the first ring, and the entire surface densely sprinkled with minute shining black warts, each emitting a tiny amber-coloured spine with a cleft knobbed apex. The head is blackish marked with ochreous lines. It still resides in a tube of grass spun closely together, and feeds on any other kind of grass that happens to be interwoven with the Aira. Just before pupation the caterpillar often crawls restlessly about, but in some instances it does not leave its place of feeding, and spins a strong, coarse network cocoon among the grass close to the ground, weaving the gnawed loose pieces of grass with the fine stems and blades, and therein pupates during the latter part of July.
The chrysalis is secured in the cocoon by hooks at the tail and by hooked bristles on the head; the head and thorax are pale olive mottled with blackish; the body olive, spotted with dark olive, and inclining to yellow on the ventral surface; below each spiracle is a short longitudinal mark; the spiracles are amber-brown.
The butterfly is to be found in August on most of our chalk hills, but has not been recorded from either Scotland or Ireland.
It is a very quick flyer and difficult to capture when on the wing, but it is fond of sitting on low-growing thistles, and is then sometimes easy to take. Abroad it occurs throughout Europe and Northern Asia to China and Japan.
The Chequered Skipper (Carterocephalus palæmon).
The well-defined yellow or orange spots on the blackish-brown ground colour distinguish this butterfly from all other British Skippers.
The variation is only of a minor kind, and chiefly in the direction of an increase or a decrease in the number and the size of the spots. Occasionally those on the central area of the fore wings are much enlarged and more or less confluent; and the spots on the outer margin of the hind wings are sometimes very small or entirely absent.
The following particulars of the early stages are abstracted from Mr. Frohawk’s life-history of the species (Entomologist, 1892):—
Living females received in June were placed on a growing plant of brome grass (Bromus asper), and a few eggs were deposited, some upon the blades of grass, others upon the gauze-covered glass jar in which the plant was placed; they were laid singly, firmly adhering to whatever laid upon. The first lot of eggs were deposited on June 14. The egg has a pearly appearance, being whitish or yellowish-white in colour. Ten days after the egg is deposited the young caterpillar emerges by eating away the crown. Soon after hatching out the young caterpillar makes a little tubular dwelling, drawing together the edges of the grass-blade by spinning about three or four stout cords of silk, which quickly contract, causing the edges to draw together, and sometimes to overlap, forming a compact short tube; generally before spinning it nibbles off the extreme edge of the blade where the silk is afterwards attached. It feeds upon the blade both above and below its abode, devouring so much that frequently only the midrib of the blade remains, and the tube only just long enough to conceal it; it then shifts its quarters, and prepares a new home.
On October 3, when one hundred and one days old, the caterpillar was pale primrose-yellow, and the stripes of a slightly darker hue, the white lateral line showing clearly, and spiracles brownish; the head pale buff with a faint lilac tinge, with a black patch above the mouth and brownish at the sides. In the previous stage the caterpillar was whitish-green with a rather dark green line along the middle of the back, this line bordered on each side by an almost white, very fine line, followed by alternate darker and lighter lines, the lightest being extremely fine; “then a subdorsal darker green line, bordered laterally by a conspicuous whitish line, which is again bordered below by a paler and indistinct green line, and a very faint spiracular whitish stripe, on which the spiracles are placed; they are white, outlined by a dark but indistinct ring; the under surface is whitish-green.”
About the middle of October the hibernaculum was formed by spinning two blades of grass together at the edges, so making a tube, in which the caterpillar remained during the winter. On March 21 it left its retreat, but did not seem to feed, and generally remained quiet, lying along a grass-blade. On April 3 “it had drawn together with silk six blades of grass at the ends, forming a tent-like structure, and along the surface of one of the broadest a little carpet of silk was spun, upon which it rested with its head uppermost; a silk cord also encircled its body round the fourth segment.” It assumed the chrysalis state on April 8, and had then passed two hundred and eighty-nine days in the caterpillar condition. The chrysalis measures five-eighths of an inch in length, is fairly cylindrical, but tapering to the tail. “Dorsal view: the head is pointed in front in the form of a short conical beak; the eyes are rather prominent; the thorax is swollen in the middle, the widest part, and then gradually tapers towards the last segment, which is elongated and flattened. Lateral view: the beak is slightly upturned, the thorax convexed, and the segment next to the thorax is rather swollen in the middle, so forming a rather decided depression at the base of the thorax, where the silken cord passes round; the body gradually tapering to the last segment, which terminates in a long compressed curved process furnished with long hooks; the wing-cases extend down two-thirds its length, and only very little, if at all, swollen; the antennæ and legs are but feebly modelled; the tongue is well defined, it is dusky at the base, blending into black at the apex; the colour is of a very pale primrose-yellow, shading into pearly grey, and semi-transparent on the head, wings, and flap; a dark medio-dorsal line commences at the base of the beak, and passes down the entire length, gradually fading off in the anal extremity; it is blackest on the head and first abdominal segment, and palest on the thorax, where it is light brown; there are two rust-red subdorsal lines, which run parallel from the base of the antennæ to the last segment; another similar line, united along the inner margin of the wing, passes over two spiracles, and then runs parallel with the subdorsal lines.... The antennæ and wings are faintly outlined with dusky brown. In general appearance and colouring the pupa closely resembles a piece of dead withered grass.”
A female butterfly emerged on May 20, the transformation from egg to perfect insect thus occupying about eleven months. This local butterfly is on the wing in June; sometimes it is seen in the latter part of May, and, more rarely perhaps, in July.
This species appears to have been first noticed as an inhabitant of Britain in 1798, in which year specimens were taken in Clapham Park Wood, Bedfordshire, by Dr. Abbott, who, four years later, also reported the butterfly from White Wood, Gamlingay, Cambridgeshire. In 1823 it was found to occur at Castor Hanglands, near Peterborough; and in 1841 Doubleday met with it, in large numbers, in Monk’s Wood, Huntingdonshire. Among other localities from which it has been reported are Ropsley Wood, near Grantham, Notts, and Wychwood Forest, Oxfordshire.
In its special localities, which, at the present time, are chiefly the larger woods in Lincolnshire, Northamptonshire, and Buckinghamshire, it frequents the flowers of ground ivy (Nepeta glechoma) and of the bugle (Ajuga reptans).
Abroad it is locally common in various parts of Central Europe; also occurs in Finland, Central and Northern Russia, Dalmatia, Piedmont, and in Labrador, and other parts of North America.