122 



LEPIDOPTERA. 



The Silkworm (Bombyx Mori}. 



Its caterpillar has a smooth body, and at its birth is scarcely aline in length, 

 but attains to even more than three inches. In this form the silkworm lives 

 about thirty-four days, and during that period changes its skin four times. It 

 feeds on the leaves of the mulberry ; at the time of moulting it does not eat, 

 but after changing its skin its appetite is doubled. When it is ready to change 

 into a chrysalis, it becomes flaccid and soft, and seeks a proper place where 

 to construct a cocoon, in which it encloses itself : the first day is occupied in 

 attaching, in an irregular manner, threads of silk to neighbouring objects to 

 support it ; on the second day it begins to multiply these threads, so as to en- 

 velope itself, and on the third day it is completely enclosed in its cocoon. This 



FIG. 123. SILKWORM ox MULBERRY-LEAF. 



nest is formed of a single filament of silk wrapped around the animal, and its 

 turns are glued together by a kind of gum. It is estimated that the length of 

 the filament in an ordinary cocoon is nine hundred feet. The form of the 

 cocoon is oval, and its colour either yellow or white. 



The Bombyx remains in the chrysalis state in the interior of its cocoon about 

 twenty days, and when it has finished its metamorphosis, disgorges upon its 

 walls a peculiar liquid, which softens it, and enables the animal to make a 

 round hole through which to escape. To obtain the silk produced by these 

 animals, it is, therefore, necessary to kill them before they pierce the cocoon, 

 and then wind or reel off the thread or filament of which it is composed. To 

 unglue it, the cocoons are soaked in warm water, then the filaments of three 

 or four are united into one thread. That part of the cocoon which cannot be 

 reeled off in this way is carded, and constitutes floss silk. 



The mulberry bombyx is not the only moth that yields silk that 

 can be usefully employed. The inhabitants of Madagascar make 

 use of a species, the caterpillars of which live in numerous bands, 



