Larvae feed gregariously but disperse just prior to pupation, where they may travel quite some distance.
The primary larval foodplants are Elms (various) (Ulmus spp.), Poplars (various) (Populus spp.) and Willows (various) (Salix spp.).
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"The larva begins making its exit by nibbling tiny holes in a circle round the crown of the egg; this continues until it is completely cut round; then the larva pushes off the cap and emerges. It immediately starts spinning a carpet of silk as it crawls away, spinning as it goes crawling to the extremity of the branch. They all do precisely the same, and at once congregate, forming a colony on the last cluster of leaves, covering the bases with web, on which they live and feed in company. The batch of larvae hatched on May 3rd; thus remained in the egg state nineteen days. This batch (the first laid) contained 192 eggs, all of which hatched excepting one. On May 5th another batch hatched, and all did the same as the first lot; and on the 16th a very large batch of eggs hatched which were laid on the same branch as those hatched on the 5th, and directly the larva emerged they all started spinning and crawling up the branch till they arrived at the part already covered with web by the previous brood, and, following the web-covered branches, every individual of the large batch ascended and joined the elder company, which were eleven days old. The two families then formed one big community, those just hatched nestling among their larger companions. The following day another large family hatched, which divided into two companies and lived separately from the first. The larva, directly after emergence, measures 1.8 mm. long; the head is large and shining black, and a few fine black bristles are scattered over the surface; the segmental divisions are clearly defined, each segment having about four transverse wrinkles and ten black hairs (five on each side); those on the dorsal surface are very long, slightly curved, and three in number above the spiracle; immediately behind the spiracle is another, which projects laterally; and slightly in front, and below the spiracle, is the fifth, which curves downwards; all these are black, with shining black bulbous bases; the surrounding skin is bare of the minute black granulations which cover the whole of the surface of the body; these bare places form a pale circular disc round each hair, and also the spiracles, which are black; the claspers are granulated with black at the base, and have two whitish spines directed downwards; the foot is large and furnished with very ample claws. The entire colouring of the body is pale olive-brown, inclining to citron. The larvae always rest in a dense mass, all crowded together, some on top of the others; they cover the leaves with web. As soon as the leaves are stripped of the cuticle, the entire company move to a fresh supply. If disturbed they curve upward the anterior portion of the body and remain in that attitude for a short time. When the whole company are slightly on the move in the sun they present a curious sparkling mass, clue to the immense number of glistening black heads. Shortly before the first moult the larva measures 5.4 mm. long. It is uniformly cylindrical, the segments deeply incised and very glossy. The ground colour is amber-brown, with a medio-dorsal series of longitudinal dark brown marks, and mottlings of the same colour form a dark spiracular band; the spiracles are also amber-brown; the sub-dorsal series is freckled with brown. When undergoing the change for moulting they occasionally move about on the web-covered leaves, a habit unusual among other species of butterflies." - Frohawk (1924)
"The first moult occurred on May 20th. Directly after moulting the head is ochreous, but in a very short time turns jet-black and shining; also there are ochreous dorsal markings which soon change to dull brown. Before the second moult, when twenty-three days old, it measures 10.2 mm. long; the body is covered with minute black points, which are so *small that they give the glossy surface a granular appearance; besides these, tiny black warts are sprinkled over the whole surface; these vary much in size, and each one emits a tiny black hair; there are also longitudinal rows of small black tubercles; the first is medio-dorsal, the second sub-dorsal, the third super-spiracular, and the fourth sub-spiracular; each of these terminates in a rather long, slender, curving, black bristle, and several shorter ones spring from the sides of each tubercle; the spiracles are black; the ground colour is brown freckled with ochreous, and a broad band of the latter colour, broken up by a medio-dorsal series of dark markings, occurs as in the previous stage; the head is shining black and beset with hairs, the legs shining black, the claspers clear ochreous-yellow, and of the same colour as the dorsal band. The larvae feed on the topmost leaves, at first eating the basal portion, and by their weight causing the leaves to hang clown until their ends rest on the leaves below; they feed on these in turn, and continue in this manner to work their way downwards, feeding as they go, eating all the leaves and covering everything with web." - Frohawk (1924)
"Second moult on May 27th. Before the third moult, twenty-nine days old, it measures 17.2 mm. long. The ground colour is a deep ashy or purplish-black; the dorsal band orange, broken up with black markings as in the former stage. Immediately below the spiracles are very faint crescentic markings, almost invisible; the tubercles of the previous stage are now developed into moderately long, black, spine-like tubercles, each terminating in a longish, curved white bristle, and numerous much smaller lateral hairs, and all the minute body-warts bear white hairs instead of black, as in the last skin; the head and legs are shining black, with fine white hairs; the claspers are amber colour. The spines of the medio-dorsal series are very short, and commence on the sixth segment and end on the eleventh, one on each of these six segments. They still remain gregarious. When one branch is denuded of leaves they all descend until reaching another branch, which they ascend to the end, and, again clustering together in a mass, feed downwards as before; when moving they are extremely active, and feed rapidly. Warm weather greatly influences the rapidity of their growth, cold retarding them considerably." - Frohawk (1924)
"Third moult on June 3rd. Before the fourth moult, thirty-four days old, it measures 31.8 mm. long; the ground colour is velvety black, otherwise very similar to the previous stage, but the dorsal orange band is richer and deeper in colour, and there are numerous very small pearly-white warts sprinkled over the body, mostly forming circles round each segment on the two posterior wrinkles; these, as well as the minute black warts, emit fine, curved white hairs; the black spines also bear fine white hairs; the dorsal spines terminate with black, spine-like bristles; the super and sub-spiracular spines end with longish, curved white hairs with black tips; the black head is bilobed and cleft on the crown and covered with white hairs; legs shining black; claspers bright tawny, excepting the anal pair, which are black; on the eleventh segment is a small, medio-dorsal, shining black disc, and on the twelfth segment is a much larger one, which closely resembles the head." - Frohawk (1924)
"After fourth and last moult, when fully grown, the larva measures 54 mm. long, of almost uniform thickness, excepting the first segment, which is much the smallest. The head is bilobed, having a deep notch on the crown, and of a dull black colour, covered with black warts, each emitting a white hair. The segmental divisions are deep, each segment being swollen in the middle and transversely wrinkled on the posterior half; the spines are long and tapering to a very long point, shining black, and bear a number of fine white hairs, each having a black swollen base; the two anterior pairs of dorsal spines are branched, each having two; the first segment is spineless. The arrangement of the spines is as follows: four each on the second and third segments; these are the longest spines on the body and are placed sub-dorsally and laterally; six each on the fourth and fifth, and seven each on all the remaining segments, excepting the last, which has four sub-dorsal ones, making in all sixty-six spines. From the sixth to eleventh segments (both inclusive) each has a short mcdio-dorsal spine, which is absent from the rest; the other spines, on the fourth to eleventh segments inclusive, form sub-dorsal, super-spiracular and sub-spiracular rows. The ground colour is a deep velvety black, the surface is minutely but roughly granulated, being covered with extremely minute points and densely sprinkled with pearl-white warts, each emitting a fine white hair, some being of considerable length and the majority slightly curved. They curve in different directions, giving the larva a soft, silky or velvety appearance from the varied play of light falling on the hairs. The segmental divisions are bare, as well as the interstices of the wrinkles, which appear of a deep velvety black; down the centre of the back is a series of rich, deep, rust-red, shield-like markings, which commence on the third segment and terminate on the eleventh segment, the first being the smallest and composed of four spots; the two anterior ones are very small; the red runs along each side of the medio-dorsal spine, and behind it in the middle of the red are three black markings; all the red markings have the surface granular like the rest of the body, and scattered with similar hairs, but the base of each is yellowish; in the centre of the anal segment is a shining black dorsal disc, much resembling the head; the spiracles are black and inconspicuous, the legs are black and shining, and the four pairs of middle claspers are a burnt sienna or rust colour, with a polished chitinous band above the feet, which are amply furnished with hooks; the anal pair are black with pale reddish feet. The larvae are gregarious until full fed; they then become very restless, leave the tree, and crawl rapidly about in search of a suitable place for pupation. The first became full fed on June 20th, when several started crawling restlessly about. After crawling for six hours, they finally rested close together, and were observed from time to time to be spinning pads of silk, as well as a layer of silk to rest upon, and attaching the anal claspers to the pads, and then settled down for pupation. Next day one after the other became suspended, and the following day (June 22nd) they all pupated. Like the larvae of other Vanessidae, E. antiopa are very sensitive to any disturbance; any sudden noise sufficient to cause concussion of the air causes the whole brood to give a violent jerk. By this instantaneous movement of several hundred larvae in a dense mass a very curious effect is produced, and, I should imagine, is somewhat alarming to any insectivorous bird that might approach them too closely. This habit exists through all the larval stages. Whether this is a protective habit or not cannot be said, but the spines in the last two stages, especially after the fourth moult, are so sharply pointed that they readily pierce the hand. Therefore, if occasion offered, such efficient weapons of defence would afford considerable protection to the larvae. Both sallow and willow are equally suitable food for the larvae, and birch is readily eaten, even when willow has formed the sole food until the last stage; they will also feed on elm. Nettle was not appreciated by the larvae, not being touched by them during the last two or three stages; only when first hatched did they feed upon it; although they lived upon nettle for several days they did not thrive, and eventually died, while almost without exception all the other larvae, about 2,000, throve and pupated which had fed on the other food named." - Frohawk (1924)
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The pupa hangs upside-side attached by its cremaster to a leaf stem or twig. This stage lasts around 3 weeks.
"The pupa measures in total length, including the cremaster, from 25.4 mm. to 31.8 mm. The average of the male pupa is 25.4 mm. and that of the female 28.6 mm., but large females attain as much as 31.8 mm. Side view: The head is beaked in front, the thorax angular, rising to a pointed dorsal keel, and sloping posteriorly to the sunken meta-thorax; the abdominal segments rise to the third, then decreasing and curving to the anal segment, which terminates in a long, slightly curved cremaster, furnished with an ample cluster of hooks; the ventral surface forms a fairly straight line, except bulging at the apex of the wings. Dorsal view: The head terminates in two well developed points. There are three points which project laterally on the wing: the first on the base, the second on the inner margin, and the third near the anal angle; between these points the outline is concave, the abdomen gradually tapers to the anal segment, the cremaster is broad, flattened, rounded at the end, and has a sunken centre. On the fourth, fifth, sixth, seventh and eighth abdominal segments is a mcdio-dorsal black point and a sub-dorsal series of six prominent points, commencing on the second segment and ending on the seventh segment; those on the eight and ninth segments are very small; that on the fourth segment is the largest; they have pale bases, black centres and orange tips; there are also two rows of small black tubercles, the first super-spiracular, the second sub-spiracular; each row is composed of a single tubercle on each segment; the spiracles are narrow transverse apertures of a dusky colour. The dorsal half of the head and wing points are black and the ventral half orange. The whole surface is finely and irregularly furrowed and granulated. The ground colour is a pale buff, covered with fine fuscous reticulations. The entire surface is clothed with a whitish, powdery substance, giving a pale lilac or pinkish bloom to the pupa, which, however, is easily rubbed off, the pupa then assuming a brownish hue. There is no variation in the colouring of the pupae; every one of some 2,000 examined was precisely as described. Immediately the pupa rids itself of the larval skin, it is so vigorous in its efforts to anchor the cremastral hooks firmly into the silken pad by its twistings and twirlings that they sometimes tear themselves away and fall to the ground. The pupa is suspended by the cremastral hooks to a rather dense pad of silk spun upon the surface of whatever the larva selects for the purpose near the tree upon which it fed. From this large number of pupae (about 2,000) the butterflies began emerging during the middle of July and continued until the middle of August, many of exceptionally large size, the largest female measuring exactly 88.8 mm. in expanse." - Frohawk (1924)
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