INSECTS, 22jJ 



changing their skins. They are, in general, ex- 

 tremely voracious, often devouring more than their 

 own weight in the course of twenty-four hours. 



As soon as all their parts become perfected, and 

 they are prepared to appear under a new form, in 

 a pupa or chrysalis*, they fix upon some convenient 

 place, where they are least exposed to danger, for 

 the performance of the arduous operation. This is 

 essentially necessary, since, in their transformation, 

 they have neither strength to resist, nor swiftness 

 to avoid, the attack of an enemy. That power, 

 which instructed the parents to deposit their eggs 

 in a proper receptacle, at this critical period directs 

 the offspring in the most secure and appropriate 

 situation for their future defenceless state. Some 

 of them, as in many of the Moths, spin webs or 

 cones, in which they inclose themselves ; others 

 undergo their change in decayed wood ; and others 

 conceal themselves under the surface of the earth. 

 The larvae of Butterflies spin a little web, just suffi- 

 cient to suspend themselves by to the substance 

 they fix upon. — Preparatory to the transformation, 

 the larvze cease to take any food, and, for some 

 days, continue in a state of inactivity. During this 

 time the internal organs are gradually unfolding 

 themselves. When the completion is at hand, many 

 of them may be observed alternately to extend and 

 contract their bodies, to disengage themselves from 

 the caterpillar skin. The hinder parts are those 



first liberated : when this is done, the animals con- 



■ — . — - ■ — ~ 



* The chrysalis is occasionally called Aurelia, Bean, Cod, Cope de 

 Nymph. 



VOL. Ill, Q 



