Chrysalis, a name generally limited to the second stage of the growth of lepidopterous insects, or to the pupa from a caterpillar, because, as the term implies, they are sometimes gilt or ornamented with golden spots; aurelia is synonymous with chrysalis. When the limbs are not covered, the term nymph is applied to insects in this stage, more especially when the grubs cat; and the word pupa is properly employed for those which entirely lose the larva form, take no food, and remain motionless, bound up like a swathed mummy. The chrysalis, like all pupa) which undergo a complete metamorphosis, is motionless and does not eat. On a close examination, traces of the head and its organs, the wings, and the legs, may be seen closely pressed to the body and adherent to it by a kind of varnish. Some arc angular and covered with protuberances, but most are smooth and spindle-shaped. The manner in which the perfect insects come out has been described in the article Butterfly, where also are mentioned their various modes of suspension. Most are contained in a cocoon, from which exit is easy for the insect by the disposition of the threads at one end.
Those of the butterflies are uncovered and fixed by the posterior portion, and usually open in a few days, while in others the chrysalis state lasts through the winter, either in the open air, underground, in holes in walls and trees, or in silken cocoons. Some of the social caterpillars remain in company in the chrysalis state, each constructing a cocoon at the end of their last nest. The most useful of these cocoons is that of the silkworm; but other caterpillars form coverings more remarkable in shape and presupposing greater intelligence in the makers. As in the previous stages of the metamorphosis, the chrysalis opens on the back to give exit to the perfect insect.
Chrysalis of large Tortoise-shell Butterfly, magnified. 1. With the upper parts opened. 2. With the upper parts pressed down and adhering to the body.