LEPIDOPTERA. 



163 



This nest is formed of a single filament of silk wrapped 

 around the animal, and its turns are glued together by 



FIG. 123. SILKWORM ON MULBERRY-LEAF. 



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. 



FlG. 124. FEMALE SILKWORM MOTH AND EGGS. 



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 



