Our Garden-White, Brimstone, Clouded-yellows and Orange-tip butterflies belong to this family; as does also the South American genus formerly called Leptalis. This generic name, which is much mentioned in literature owing to the resemblance of the species of the genus to Heliconiides, has now disappeared; Leptalis having been divided into various genera, while the name itself is now considered merely a synonym of Dismorphia.
The African Insect, Pseudopontia paradoxa, has nearly transparent wings, no club to the antennae, a remarkably small cell on the wing, and an arrangement of the nervules not found in any other butterfly; there being only ten nervules at the periphery of the front wing, and both upper and lower radial nervules uniting with the posterior branch of the subcostal. It has been treated as a moth by several entomologists. Aurivillius considers that it is certainly a butterfly; but as the metamorphoses are unknown, we cannot yet form a final opinion as to this curious form. The extraordinary Peruvian Insect, Styx infernalis, is also placed in this family by Staudinger; it is a small, pale Insect, almost white, and with imperfect scales; a little recalling a Satyrid. It appears to be synthetic to Pieridae and Erycinidae.
Fig. 180—Pupation of the Orange-tip butterfly, Euchloe cardamines. A, The completed pupa; B, the larva, with its girdle, prepared for the change.
The caterpillars of Pieridae are perhaps the least remarkable or attractive of all butterfly-caterpillars; their skins are as a rule bare, or covered only with fine, short down or hair; their prevalent colour is green, more or less speckled with black and yellow, and they are destitute of any prominent peculiarities of external structure. Pupation is accomplished by the larva fixing itself to some solid body by the posterior extremity, with the head upwards (or the position may be horizontal), and then placing a girdle round the middle of the body. The pupa never hangs down freely as it does in Nymphalidae. It has been ascertained by experiment that if the girdle round the larva be cut, the pupation can nevertheless be accomplished by a considerable proportion of larvae. Some of the pupae are of very peculiar form, as is the case in the Orange-tip (Fig. 180, A) and Brimstone butterflies. The Orange-tip butterfly passes nine or ten months of each year as a pupa, which is variable in colour; perhaps to some extent in conformity with its surroundings. The North American E. genutia has a similar life-history, but the larva leaves its Cruciferous food-plant, wanders to an oak tree, and there turns to a pupa, resembling in colour the bark of the tree.
Fig. 181—Newly-hatched larva of Euchloe cardamines. A, The larva in profile; B, one segment more magnified, showing the liquid-bearing setae; C, one of the setae still more magnified, and without liquid.
It is not unusual for caterpillars to change their habits and appearance in a definite manner in the course of the larval life. The caterpillar of Euchloe cardamines exhibits a larval metamorphosis of a well-marked character. The young larva (Fig. 181) is armed with peculiar setae, furcate at the tip, each of which bears a tiny ball of fluid. In this stage the caterpillar makes scarcely any movement. In the middle of the caterpillar's life a new vestiture appears after an ecdysis; numerous fine hairs are present, and the fluid-bearing spines nearly disappear, being reduced to a single series of spines of a comparatively small size on each side of the upper middle region of the body (Fig. 182). The colour is also a good deal changed, and concomitantly there is a much greater voracity and restlessness.
Fig. 182—Larva of Euchloe cardamines in middle life. A, the larva in profile; B, one segment more magnified.