ESCAPE BACKWARDS. 285 



them together into the requisite form, become so 

 elastic as to close again when the moth has passed 

 between them, and made its escape. The cocoon 

 preserves precisely the same form after the insect 

 has quitted it as before, and it is impossible, by 

 the naked eye, to detect the place of its exit. 



Asa general rule, insects make their escape from 

 the pupa case head foremost ; but there occurs a 

 very singular exception in the case of some of the 

 gall insects. The males of these insects contrive 

 to make their escape out of the pupa case, formed 

 of the dried skin, tail foremost ; and as they thus 

 back out of their dwelling, their wings are neces- 

 sarily turned backwards over their heads ; but a 

 little exercise soon puts the ruffled insect in 

 proper plume again, and the wings resume their 

 customary position. 



Some curiosity may be felt to know in what 

 way the silk-worm moth escapes from the double 

 prison, the pupa case, and the cocoon, in 

 which she is concealed. How is the moth to 

 make its way through the dense mass of fibres 

 all glued together, which walls her in on every 

 side ? Her delicate wings and body would never 

 endure anything like the severity of the struggle 



