THE EMPEROR MOTH. 445 



When it is full-fed, the larva spins a light-brovra cocoon 

 among its food, and the perfect insect appears in the middle of 

 spring. 



This cocoon is one of the most remarkable and interesting 

 of insect habitations. Externally it is a simple brown, oval 

 structure, more pointed at one end than the other, and having 

 an outline much resembling that of a balloon. If it be care- 

 fully opened, and cut in two lougitudinally, a most remarkable 

 structure is seen. The smaller and pointed end is doublo, and 

 within the outer case is a ring of short and stiff threads, look- 

 ing much like bristles, their free ends directed towards the 

 mouth of the cocoon, which is allowed to remain open. As 

 these bristle-like threads follow the curve of the wall of the 

 cocoon, it is evident that their ends must converge so as to 

 close the opening against the entry of any insect foe, while 

 they yield to the pressure of any creature within. 



In consequence of this arrangement, the pupa remains 

 securely shut up in its habitation, and, when the time comes 

 for its assumption of the perfect state, the newly developed 

 Moth creeps easily out of the cocoon, the guardian threads of 

 which yield to its passage, and then close again, so that to all 

 appearance, the cocoon looks just as it did when it contained 

 the chrysalis. As the caterpillar is a tolerably hardy one. 

 there is no difficulty in obtaining the beautiful cocoons. 



