228 COMMON BRITISH INSECTS. 



looking much like bristles, their free ends directed to- 

 wards 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 pres- 

 sure of any creature within. 



In consequence of this arrangement, the pupa re- 

 mains 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. 



