UK Butterflies - Comma - Polygonia c-album (2024)

On emerging, the young larva moves to the underside of a leaf where it feeds. As it matures it feeds on the upperside of the leaf and is quite unmistakable, resembling a bird dropping. This stage lasts around 5 weeks, depending on temperature. Some authors state that larvae of the first brood have 5 instars while those of the second brood have 4 instars. However, Henwood (1997) shows that this is not so, with both broods going through 5 instars.

The primary larval foodplant is Common Nettle (Urtica dioica). currants (Ribes spp.), elms (Ulmus spp.), Hop (Humulus lupulus) and willows (Salix spp.) are also used.

1st Instar

"Directly after emergence the little larva measures 2.12 mm. long. The body, legs and claspers are of a pale ochreous, tinged with green, especially on the anterior segments; the fourth, sixth, eighth, tenth and eleventh segments are rather darker than the rest of the body, these five segments being of a rusty-brown hue, giving the larva a somewhat banded appearance. Each segment consists of large swollen prominences, those on the dorsal surface being very large and elevated; those on the lateral region are more compressed; those of the dorsal pair on each segment are the largest, and from the apex of each rises a long, gently curved hair which tapers off into a very fine point. Those of the sub-dorsal pair are conical in form and united at their bases, and one placed slightly above the other, the lower one being directly above the spiracle; both these terminate by a long hair, the upper one curving forwards and the lower one curving backwards. Immediately below the spiracle is a double globular wart, the anterior portion bearing two hairs, one curving slightly forwards and downwards, the other directed backwards and downwards; the posterior half bears one hair which curves upwards and backwards. All the hairs are simple, finely pointed, and have bulbous bases, excepting the dorsal ones. All are black with light tips. The claspers are very ample, and have two delicate, whitish, finely pointed spines, both directed downwards; the foot is black. The greater part of the surface of the larva has a granular effect, especially on the under surface, where it is clothed with extremely minute blackish points. The head is shining black and beset with hairs. The spiracles are black. When nine days old, and before the first moult, it measures 3.2 mm. in length. The ground colour is clear brown, inclining to ochreous, palest on the under surface, and checkered with dark brown and white, and studded with black warts, each emitting a long hair as described above, but now all the hairs are stiffened and appear as fine bristles. The dorsal half of the second, third, fifth, seventh and ninth segments are white, also the greater part of the anal segment; the remaining segments are brown dorsally (appearing dark brown from the presence of black warts on the sienna-brown ground colour), which forms a strong contrast with the white. The entire surface is particularly glossy, and the white resembles marble. The head, legs and claspers remain unchanged. The larva generally rests in nearly a straight position, but sometimes a good deal curved, in the form of a fish-hook, but more often only slightly curved. It lives entirely upon the under surface of the leaf, and spins a fine layer of silk between the ribs, upon which it rests. After each meal it turns round and, retracing its steps, rests in the same place as before, and with its head furthermost from the part eaten. It feeds upon the spines, smaller ribs and whole substance of the leaf, excepting the largest midribs, making large perforations in the leaf. During the act of defecation the larva elevates the posterior end, and curving the anterior part of its body round, it takes the excrement in its mouth and jerks it away; if not successful in its first attempt to jerk it aside, it brushes it from its mouth with the long, stiff, dorsal hairs on the hinder segments. Directly after emergence from the egg, the larva upon being touched exudes a bead of greenish-black fluid from its mouth, and remains immediately afterwards perfectly still, as if paralysed, but only for about fifteen or twenty seconds. Since the hatching of the eggs the weather remained dull and cold, the average day temperature being only about 52 degrees, therefore the growth of the larva during the first stage was undoubtedly considerably retarded." - Frohawk (1924)

2nd Instar

"The first moult occurred on May 14th, when a large number moulted. Before second moult the larva, when fourteen days old, is 5.4 mm. long, and rather stout in proportion; the ground colour is pale drab, shading into ivory-white on the lateral and under surface, checkered with brownish-black; there are seven longitudinal rows of spines, placed medio-dorsal, sub-dorsal, super-spiracular and sub-spiracular; each spine terminates in a rather long, finely pointed bristle, and bearing other shorter and very fine bristles; all the spines are black, excepting those on the fifth, seventh and ninth segments of the medio and sub-dorsal rows, which are white, the white spreading over the dorsal surface of those segments and very conspicuous. The bases of the dorsal spines on the second and third segments, as well as the greater portion of the first and last segments, are of the same ivory-white colour. There are no spines on the first segment. The head is shining black, with two short, blunt tubercles on the crown, one on each lobe, and emits a number of black bristles. The surface of the head is scattered with numerous black hairs. The legs are black and white, the claspers whitish with black extremities. They rest in the same attitude as in the previous stage, and always upon the under surface of the leaf." - Frohawk (1924)

3rd Instar

"The second moult was on May 21st. After the second moult, twenty-six days old, it measures 11 mm. long; the body is cylindrical and of uniform thickness throughout. The ground colour is of a dark olive-brown, reticulated with white along the dorsal and sub-spiracular regions; the dorsal pair of spines on the second and third segments are amber-yellow; those on the fourth segment (where the medio-dorsal series commences) are all black; the three dorsal spines of the fifth segment are paler yellow, and creamy-white on the seventh, ninth and twelfth; all are black on the sixth, eighth, tenth and eleventh segments; all the spines are furnished with very finely pointed black spinelets; the creamy-white surrounding the bases of the white and pale amber spines forms large and conspicuous markings. All other details are similar to the previous stage, and their habits are the same." - Frohawk (1924)

4th Instar

"The third moult occurred on June 21st. Shortly before the fourth moult, and thirty-four days old, it measures, while extended, 16 mm.; the ground colour is black, the sixth to tenth segments inclusive have the dorsal surface encircling the medio and sub-dorsal spines of a milky-white colour; the eleventh segment has the anterior half white. All the dorsal spines of the second, third, fourth and fifth segments are amber yellow; all the super-spiracular spines are black, and are situated on amber-yellow crescentic markings; those of the sub-spiracular series are greyish and placed on a creamy-white streak; a curved amber-yellow streak passes directly below the spiracles, which are outlined with whitish; the body is encircled by two white lines at the segmental divisions, but those on the anterior part are pale yellow." - Frohawk (1924)

5th Instar

"The fourth and last moult took place on June 8th. After the fourth moult, fully grown, forty-five days old, it measures from 31.8 mm. to 35 mm. in length, when extended while crawling. The body is almost uniform in thickness, the first and last segments only being the smallest. Each segment is much swollen round the middle, so that the larva has the appearance of being tightly girdled at the juncture of each segment There are seven longitudinal rows of spines from the fourth to eleventh segments inclusive, which are situated in the following order, each having a medio-dorsal, sub-dorsal, super-spiracular and sub-spiracular spine, the medio-dorsal spine being a little in advance of the rest. The second, third and twelfth segments have each four spines; all those on the second, third, fourth and fifth are amber-yellow, excepting the sub-spiracular, which are white; all the other spines on the body are white, excepting the super-spiracular series, which are tinged with ochreous; all the spines are branched, each branch or spinelet is tipped with amber, and each spine also emits a number of very fine white hairs. The first segment is without spines, but has a transverse series of short and slender orange tubercles, each terminated with a fine pale hair curving forwards. The head in front is flattened and square, the lobes of the crown are swollen, and each surmounted by a short, club-like knob directed forwards and outwards. Upon the clubbed apex are five or six minute orange spines, each bearing a long, fine, amber-coloured hair; other similar spines are dotted over the face. The ground colour of the head is dull black; the clypeus is outlined with pale ochreous, and a short orange streak in front on each lobe of the crown. The ground colour of the body is black, reticulated with lilac-grey; the anterior half of the body is transversely ringed with amber-yellow at the segmental divisions; and those on the posterior half are white dorsally and yellow laterally; the greater part of the dorsal surface of the second, third, fourth and fifth segments is amber-yellow; the sixth to tenth segments inclusive have almost the whole of the dorsal surface white, with a short, oblique black mark in front of each sub-dorsal spine, also a smaller black spot in front of the medio-dorsal spines and a fainter one behind. The white surrounds the sub-dorsal spines and is bordered below by velvety black, then by a rich deep orange, wavy, longitudinal super-spiracular band and a similar but paler orange sub-spiracular band, both being united by an oblique narrow streak of deep orange passing immediately behind the spiracles; on these bands are placed the spines; a short straw-yellow streak occurs anterior to, and just above, the claspers; at the base of each clasper is a row of four or five small orange warts, each bearing a fine white hair. The body has several minute warts sprinkled over the surface, each emitting a delicate white hair. The legs are shining black, the claspers grey at the base, shining black on the middle, with pale ochreous extremities. When about to suspend itself for pupation, the white on the dorsal surface changed to a greyish hue. The larvae are gregarious, living generally in small companies, but sometimes many will crowd upon a certain leaf; their habits are similar in all stages, the usual resting attitude resembling the form of a fish-hook. A larva suspended itself for pupation on June 20th, and pupated the following day, the larval state lasting forty-seven days." - Frohawk (1924)