COLOR AND PATTERN IN ANIMALS 



409 



FIG. 250. Chrysalid of swallowtail 

 butterfly, Papilio, which closely re- 

 sembles the bark on which it rests. 



resemble in color and general external appearance the surface 



of the object on which they rest. The chrysalids of various 



Pa pi !i us are indeed marvelously 



faithful imitations of bits of 



rough bark (Fig. 250). 



The larvae (caterpillars) of 



various moths, particularly Geo- 



metrid and Sphingid species, 



often appear in two color types, 



one brown and the other green. 



Poulton has shown by experi- 

 ment and observation with some 



of these species that those larvae 



reared among green leaves and 



twigs become green, while those 



on dry branches become brown. 



This variable protective resemblance, like that of Trimero- 



tropis, Galgulus, and the Papilio chrysalids, also is fixed after 



being once acquired. 



An interesting example of 

 color harmony which may be 

 classified under the head of 

 variable protective resem- 

 blance is that of the larva? of 

 Lyccena sp., abundant on the 

 flower heads of the California 

 buckeye, jEscidus californicus, 

 that blooms in Mav. The buds 



/ 



of the buckeye are green, or 

 green and rose, or even all 

 rose externally. The quiet 

 sluglike Lycsenid larvae lie 

 longitudinally along the buds 

 and their short stems, and 

 are either green with faint 

 rose tinge, especially along 

 the middle of the back, or 

 are distinctly rosy all over, 

 depending strictly upon the 



color tone of the particular branch serving as their habitat. 



The correspondence in shade of color is strikingly exact : the 



FIG. 251. Two leaf hoppers or mern- 

 bracids : The upper one, Xerophyllum 

 simile; the lower one, Cladonotus hum- 

 bertianus. (After Bolivar.) 



