The expansion of the wings varies from 2⅜ to 2¾ inches. Above, all the wings are black, becoming bronzy towards the body. The fore-wings have a band of dark red nearly across the middle, and a series of three small blue spots, and three larger white spots near the apex. The hind-wings have a broad dark red band near the termen, containing two pairs of black spots with blue centres. On the under side the fore-wings are dark brown, with a broad patch of red in the middle, and a very conspicuous eye-like mark on the costa, consisting of a black central spot surrounded by a blue ring, and encircled by a yellow crescent towards the termen. The hind-wings are brownish-grey, with many darker and paler markings; the four spots on the upper surface are faintly indicated on the under side by blackish rings and central dots; the colouring of the under side varies a good deal. It is considerably darker and duller in some specimens than in others.
The egg, which is deposited on a nettle-leaf, is barrel-shaped, ornamented with a series of longitudinal ribs meeting in a central spot on the top. It is pale green, with the ribs white. The young larva, when first hatched, is dusky-yellow, with the spines black. In about a week it moults for the first time, and is then of an almost uniform brown, with the lateral lines faintly indicated. Ten days later it again sheds its skin, after which time the white lateral markings are considerably stronger. The full-grown larva varies from black to reddish-brown, with interrupted pale lateral and dorsal lines. On the third and fourth segments there are four spines, on the fifth to eleventh seven spines; the twelfth segment has six spines, and the thirteenth two spines. There are numerous white dots all over the larva. The spines vary from pale green to black. The caterpillar is considerably attenuated at each end, the central portions being somewhat swollen. Length about 1½ inches.
This caterpillar constructs for itself a small tent by fastening together several of the leaves of its food-plant. In this dwelling it can feed, safely concealed from all enemies. There are two kinds of nettles constituting the food of this insect—one a small plant, which generally grows in little patches amongst ferns in the forest (Urtica incisa), the other a large shrub or tree often found in rather open situations near rivers (Urtica ferox). The shrub is easily recognised by the formidable array of long, white spines which project from the midrib of each leaf. The larvæ of V. gonerilla are much more easily collected on the tree nettle than on the dwarf species; their leafy tents being easily detected by an examination of the foliage. When once discovered the larvæ are best obtained by cutting off, with a pair of strong scissors, the leaves which form their habitations. Like most larvæ of the genus Vanessa, these caterpillars are extremely voracious and soon eat themselves out of house and home. Those feeding on the tree nettle have an unlimited supply of leaves available both for food and shelter, but in the case of larvæ, which are dependent on the dwarf nettle for their supplies, no doubt individuals must occasionally die of starvation, as we sometimes observe large patches of the Urtica incisa completely destroyed by the larvæ of this butterfly. In some seasons these larvæ may be found as early as the middle of September, and continue abundant until the middle or end of January.
When full grown, this caterpillar suspends itself by the tail to a little patch of silk, which it has spun on the under side of a leaf, having also drawn two or three other leaves around it in the same way as the feeding larva. In this situation it hangs, with the head and three anterior segments slightly curved upwards, for nearly twenty-four hours before the transformation to the pupa state occurs. I have often watched these larvæ changing, and as their manœuvres during the process exactly resemble those of Anosia erippus a special description is unnecessary. The actual transformation may be easily observed in this species, as the larvæ are common and can be obtained in large numbers. It is well worth watching, and if a good many specimens are kept at once, some of them are sure to change at a convenient time for observation. The pupa varies from pale yellowish-brown to dark purplish-brown, darker on the wing-cases and ventral surface. The spines on the back are golden. The whole insect is also speckled with brown or black dots. The pupa varies considerably in size as well as in colour. In this insect the pupa state is of very short duration, usually only lasting about a fortnight. I am informed by Mr. Helms that the pupa of Vanessa gonerilla is often destroyed by the common hemipteron, Cermatulus nasalis, which penetrates its shell by means of its long rostrum, and speedily consumes the liquid internal portions.
The perfect insect usually emerges early in the morning. It dries its wings for a few hours whilst resting on the old nettle-leaves which formed its home when a larva. The increasing warmth of the sunshine soon hardens the wings sufficiently to allow the new-born butterfly to fly away.
This insect is very common in most situations from January till April. It lives through the winter, appearing again on fine days towards the end of August. During the spring and early summer these hibernated individuals occur in great profusion, a few specimens always remaining until the earliest of the new ones have emerged; so that about December we may occasionally observe both hibernated and recent specimens together.
In the autumn these butterflies may be seen feeding on the flowers of the scabious and the white rata, thus preparing for their long winter sleep. In the spring, however, the insect is most abundant in the vicinity of the nettle-plants, where the females are busily engaged depositing their eggs.
I have noticed that this insect possesses the power of emitting a distinct grating or hissing noise, evidently closely resembling the sound, which has been observed to be emitted by several European species of the genus.[[50]] This sound is only made when a specimen is roused from a semi-torpid condition; and it is thought that it may be useful to the insect for the purpose of intimidating intruders during its period of hibernation.
This butterfly is a rapid flier and may often be seen pursuing a straight course high above the tree-tops, apparently migrating in search of fresh breeding-grounds. It appears to have a singular liking for hill-tops, and a specimen which has selected one of these places will keep on returning to the same spot, after being repeatedly frightened away. In such situations, if the weather be calm and sunny, we may frequently see two specimens engaged in aerial battle. They fly upwards, and coursing round each other with great velocity, almost disappear in the clear blue sky. A few seconds later the two insects, gently fanning their wings in the warm sunshine, are again seen in their respective places.
VANESSA ITEA, Fabr.