26 ANIMAL BIOLOGY 



moths. One of these is Samia cecropia. The larva 

 lives on the leaves of several kinds of trees; preparatory to 

 going into the pupa stage it spins a cocoon of silk which is 

 secreted by a pair of large glands opening upon the small 

 lower lip. The cocoons are attached by one side to a 

 twig and are formed of very tough material which is 

 admirably adapted to keep out cold and moisture. The 

 pupa passes the winter within this cocoon and the mature 

 moth emerges in the spring. With no biting mouth parts 

 the moth would be utterly unable to get out of its tough 

 envelope, were there not left at one end an opening filled 

 only with loose webby material through which it can push 

 its way. A related species spins its cocoon against the 

 side of a leaf so that the leaf becomes partially wrapped 

 around it; and, as if to guard against its cocoon falling 

 off the tree when the leaves are shed in the fall, the larva 

 spins along the leaf stem a number of threads of silk 

 connecting leaf and cocoon with the twig. 



Perhaps the most beautiful of our moths is the large 

 luna moth, easily recognized by its pale green color and 

 by the swallow tails on its hind wings. Its larva feeds 

 on the leaves of the hickory, walnut and other trees and 

 forms a cocoon in which leaves are interwoven with the 

 silk. 



The moth most valuable to man is undoubtedly the 

 silk- worm moth, Bombyx mori, which is a native of China 

 where silk culture has been carried on for many centuries. 

 The larvae preferably feed upon the leaves of the mulberry 

 although they will eat the common osage orange and a 

 few other plants. The white or yellowish cocoon which 

 the larva spins is constructed of a single thread which is 

 generally over 1000 feet long. This thread is wound off 

 on reels by the silk grower and then put through various 

 processes of preparation according to the kind of silk 



