20S INSECTS OF MASSACHUSETTS. 



When the caterpillar has thus prepared itself for the approach- 

 ing change, by repeated exertions and struggles it bursts open the 

 skin on the top of its back, withdraws the forepart of its body, 

 and works the skin backwards till the hinder extremity is extri- 

 cated. It then no longer appears in the caterpillar form, but has 

 become a pupa or chrysalis, shorter than the caterpillar, and at 

 first sight apparently without a head or limbs. On close exami- 

 nation, however, there may be found traces of a head, tongue, 

 antennae, 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, antennas, 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 shrivel- 

 ed ; soon, however, the wings stretch out to their full dimensions, 

 the superfluous moisture of the body passes off, and the limbs ac- 

 quire 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 antenna? 

 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, and instead thereof we 

 find a slender tongue, by means of which liquid nourishment is 

 conveyed to the mouth of the insect, and its stomach becomes 

 capable of digesting only water and the honeyed juice of flowers. 



Ceasing to increase in size, and destined to live but a short 

 time after their final transformation, butterflies and moths spend 

 this brief period of their existence in flitting from flower to flower 

 and regaling themselves with their sweets, or in slaking their 

 1 hirst with dew or with the water left standing in puddles after 



