LEPIDOPTERA. 227 



of shroud or cocoon, into which some interweave the hairs of 

 their own bodies, and some employ, in the same way, leaves, 

 bits of wood, or even grains of earth. Other caterpillars sus-" 

 pcnd themselves, in various ways, by silken threads, without 

 enclosing their bodies in cocoons; and again, there are others 

 which merely enter the earth to undergo their transformations. 



When the caterpillar has thus prepared itself for the ap- 

 proaching change, by repeated exertions and struggles it bursts 

 open the skin on the top of its back, withdraws the fore part 

 of its body, and works the skin backwards till the hinder ex- 

 tremity is extricated. It then no longer appears in the cater- 

 pillar form, but has become a pupa or chrysalis, shorter than 

 the caterpillar, and at first sight apparently without a head or 

 limbs. On close examination, however, there may be found 

 traces of a head, tongue, antennce, wings, and legs, closely 

 pressed to the body, to which these parts are cemented by a 

 kind of varnish. Some chrysalids are angular, or furnished 

 with little protuberances; but most of them are smooth, 

 rounded at one end, and tapering at the other extremity. 

 While in the pupa state, these insects take no food, and 

 remain perfectly at rest, or only move the hinder extremity of 

 the body when touched. After a while, however, the chrysalis 

 begins to swell and contract, till the skin is rent over the back, 

 and from the fissure there issues the head, antennae, and body 

 of a butterfly or moth. When it first emerges from its pupa- 

 skin the insect is soft, moist, and weak, and its wings are 

 small and shrivelled; soon, however, the wings stretch out to 

 their full dimensions, the superfluous moisture of the body 

 passes off, and the limbs acquire their proper firmness and 

 elasticity. 



The conversion of a caterpillar to a moth or butterfly is a 

 transformation of the most complete kind. The form of the 

 body is altered, some of the legs disappear, the others and the 

 antennae become much longer than before, and four wings are 

 acquired. Moreover the mouth and digestive organs undergo 

 a total change; for the insect, after its final transformation, is 

 no longer fitted to subsist upon the same gross aliment as it 

 did in the caterpillar state ; its powerful jaws have disappeared, 



