SKLV SHEDDING. 



57 



attached by its abdominal legs to the under surface of the tv/ig 

 or leaf upon which it has been feeding. Many species spin a slight 

 web, or carpet of silk, in which they attach their posterior legs, 

 as observed by Pallas in Apatnra iris (Purple Emperor), and in 

 this manner await their change, which appears to be attended with 

 much uneasiness to the insect. The whole body is wrinkled and 

 contracted in length. In the Sphinx this contraction occurs to 

 so great an extent in some of the longitudinal muscles of the 

 anterior and middle part of the body, that the larva assumes 

 that peculiar attitude from whence the genus derives its name. 

 In this attitude the larva remains for several hours, during which 

 there are occasionally some powerful contractions and twitchings 

 of its whole body; the skin becomes dry and shrivelled, and is 

 ► gradually separated from a new but as yet very delicate one which 

 has been formed beneath it, and the three or four anterior seg- 

 ments are greatly enlarged on their dorsal but contracted on their 

 under surface. After several powerful efforts of the larva, the old 

 skin cracks along the middle of the dorsal surface of the second 

 segment, and by repeated efforts the fissure is extended into the 

 first and third segments, and the covering of the head divides 

 along the top. The larva then gradually presses itself through 

 the opening, withdrawing first its head and thoracic or fore legs, 

 and subsequently the remainder of its body, slipping off the skin 

 from behind, like the finger of a glove. This process, after the 

 skin has once been ruptured, seldom lasts more than a few minutes. 

 When first changed, the larva is exceedingly delicate, and its head, 

 which does not increase in size until the skin is again changed, is 

 very large in proportion to the rest of its body. In a few hours 

 the insect begins to feed again most voraciously, particularly after 

 it has entered its last skin, when its growth is most rapid. Thus, 

 a larva of Sphinx ligiistri, which at its last change weighed only 

 about nineteen or twenty grains, at the expiration of eight days, 

 when it was full grown, weighed nearly 120 grains. 



" Most larvai remove to fresh plants immediately after chang- 

 ing their skins, but some, as the larvae of a beautiful motii, 

 Episema cccruleocephala, devour their old skins almost immediately 

 they are cast, and sometimes one another, when deprived of food. 

 But it is not merely the external covering which is thrown off 



