140 



ORGANIC EVOLUTION 



behavior of the caterpillar of the puss moth : " The larva 

 of the puss moth (Centra v inn Id] is very common upon pop- 

 lar and willow. The circular domelike esfgs are laid either 



OC^ 



singly or in little groups of two or three, upon the upper 

 side of the leaf, and being of a reddish color strongly suggest 

 the appearance of little galls or the results of some other in- 

 jury. The youngest larvae are black, and also rest upon the 

 upper surface of the leaf, resembling the dark patches which 



b 



FlG. 40. Caterpillar of the large elephant hawk-moth (Cliierocaiiipci cV/v//<>;-). [After WEIS- 

 MANN and PoULTON.] 



a. In normal position when feeding, b. In "terrifying attitude." Compare Plate 79, Fig. .-/, 

 which shows the same caterpillar in natural colors. 



are commonly seen in this position. As the larva grows, the 

 apparent black patch would cover too large a space, and 

 would lead to detection if it still occupied the whole surface 

 of the body. The latter gains a green ground-color which 

 harmonizes with the leaf, while the dark mark is chiefly con- 

 fined to the back. As growth proceeds the relative amount 

 of green increases, and the dark mark is thus prevented from 

 attaining a size which would render it too conspicuous. In 

 the last stage of growth the green larva becomes very large, 



