4 8 



ELEMENTARY ENTOMOLOGY 



FIG. 59. Cocoon of the rusty tussock moth, made of silk 

 with the hairs of the caterpillar intermingled. (Enlarged) 



stage, usually inactive and taking no food, resembling neither larva 



nor adult, in which the tissues and organs of the larva are re- 

 constructed into 

 those necessary 

 for the winged 

 adult. In many 

 pupae the wings 

 and legs of the 

 adult are clearly 

 distinguishable, 

 closely folded 

 to the sides of 

 body, but in the 

 others the outer 

 skin of the pupa 



is only a firm shell with bare outlines of the adult forming within. 



Before the last molt many larvae burrow into the ground, where 



they hollow out cells, sometimes 



lined with silk or cement, or find 



other suitable secluded places 



in which to pupate. The cater- 

 pillars of moths and many other 



larvae spin a firm casing of silk, 



called a cocoon, in which they 



pupate. Butterfly caterpillars lash 



themselves to the food plant by 



one or two thick strands of silk, 



and the pupa, which is known 



as a chrysalis, hangs suspended 



by the tip of the abdomen with 



no cocoon. In many cases in- 

 sects hibernate over winter in 



the pupal stage, so that the time 



of the pupal life varies from a 



few days in summer to nine or 



ten months, according to the 



habit of the species. Finally, ^ , .. 



bic. 60. Cocoons or tiger moth cater- 

 the pupal Shell Splits Open and pillars on underside of loose bark 



