THE BUTTERFLY 



43 



in China, Japan, Italy, and France. Tlie method of culture 

 is as follows : The eggs ("grains ") are laid in the autumn, kept 

 over winter in a dry, airy, and co(j1 place, and hatched when the 

 mulberry begins to send out its leaves. On these leaves the 

 larvae are put to feed, and after 

 a month they begin to spin. 

 For commercial purposes the 

 larvae are induced to spin the 

 cocoons on prepared tmgs or 

 straw. A few days after the 

 cocoon is completed its in- 

 haliitant is killed in hot water. 

 The cocoon is made of a con- 

 tinuous thread about three 

 thousand metres long, of which, 

 however, only about six hun- 

 dred metres make good silk. 

 This long thread has to be 

 unravelled. The outer end is 

 loosened by soaking the cocoon 

 in hot water; then several of 

 these ends are brought togetiier and united to form a 

 single fibre of raw silk. Another imported silk-moth 

 common in parts of the United States is the Cynthia' 

 moth, whose larva infests Ailanthus trees. True American 

 forms are tlie brown Polyphemus- moth, whose larva 

 is colored light green, with oblique yellow stripes ; the 

 Promethea' moth, whose cocoon is formed in a folded leaf 



Fig. 42. — Lar"\'a of one of the Sesi- 

 id;e boring in stem. Nat. size. 

 Photo. l\v V. H. L. 



'A poetic name of Diana, from the mountain Cynthns. 



' The name of the fabled one-eyed giant blinded bj- Ulj-sses, 



' A name in Greek mythology, 



