222 



PTILOTA. 



which forms the curious hues of a brown colour, often to be 

 noticed upon rose leaves, by eating away the internal fleshy 

 part of the leaf, leaving the two surfaces entire. When full 

 gro\Mi it eats its way out of the leaf, and crawls down the 

 branches and stem, until it has found a convenient place to 

 fix its cocoon, which is formed by stretching out its body, 

 and attaching a thread to the branch ; it then crosses its 

 body to the other side, and there fastens it. By proceeding 

 thus on all sides, keeping the hinder part of the body fixed, 

 it forms the upper part of the cocoon, or that exposed to 

 the weather, which is convex, and generally circular ; the 

 under part is oblong-shaped, to hold the pupa, and much 

 smaller. 



I now proceed to notice the mode in which the insect emer- 

 ges from its pupa skin. Ordinarily this is eff'ected as here- 

 tofore, in consequence of the increased size of some, at least, 

 of the segments of the body, especially those of the thorax ; 

 and it is now only necessary for the insect to give to its in- 

 closed body various contortions, when the skin slits generally 

 do\ATi the back, and permits the escape of the inclosed insect. 

 In chrysahdes, the slit extends gradually down the sides of 

 the wing cases, and on each side 

 of the leg cases, so that the outer 

 skin of the chrysalis may be said 

 to be split into four portions. On 

 its exclusion, the insect is soft, 

 weak, and covered with moisture. 

 The elytra and the wings, at first, 

 are but of a small size; their form 

 however, soon changes, their 

 thickness diminishes, and their 

 ordinary size is acquired, the air 

 tubes distributed throughout the 

 body, and especially in the wing, 



Tortoiscslicll butterfly, just e 

 ged Irom the chrysalis. 



