THE INSECTS 



239 



and body appear to have a thicker coating of hairs and scales, and the 

 antenniB arc feathery. The position of the wings when at rest forms 

 another eas\' waj- of dis- 

 tinguishing the one in- 

 sect from theothiT. 

 (See Figures, page 237). 

 Development. The 

 Egg. — The eggs, cream- 

 colored and as large as a 

 pinhead, are deposited 

 in small clusters on the 

 underside of leaves of 

 the food plant. The 

 young are at first tiny 

 black caterpillars, which 

 later change color to a 

 bluish green, with projec- 

 tions of blue, yellow, and 

 red along the dorsal side. 

 The Pupal Stage. — 

 Unlike the butterfly, the 

 moth passes the quies- 

 cent stage in a case of 

 silk or other material 

 called a cocoon. The co- 

 coons ,of cecropia may 

 be found in the faU on 

 willows or alders. Such 

 cocoons found in mead- 

 ows or fields are usuaUy 

 larger than those found on the hillsides, probably because of a difference 

 in the food supply of the larva which spun the cocoon. 



If the cocoon is cut open lengthwise (see Figure), the dormant insect or 



chrysalis wiU be found to- 

 gether with the cast-off skin 

 of the caterpillar which spun 

 the case. 



Silkworms. — The Ameri- 

 can silkworm (Tcica pohjphc- 

 iiius) is another well-known 

 moth. The cocoons, made 

 in part out of the leaves of 

 the elm, oak, or maple, fall 

 Polyphemus, one half natural size. Photo- lo the ground when the 

 graphed by Davison. leaves drop, and hence are 



Life hi.story of the cecropia moth. Alcove, the adult ; 

 the larva (caterpillar) in center ; the pupal case to 

 right, below ; the same cut open at left, below. 

 From photograph loaned by the American Mu- 

 seum of Natural History. 



