VII 



DEFENCES OF INSECTS 



263 



It has been urged that mimetic colouration is due to 

 " external conditions," since female Pieridae are 

 mimetic of the Heliconidae with which they associate, 

 while their males whose habits are different are non- 

 mimetic. The fact that the same resemblances occur 

 where the two sexes are alike in habit and fly in the 

 same localities, entirely disproves this theory. Nor 

 is it more feasible to ascribe to " heredity " or rever- 

 sion to ancestral types a resemblance which exists 

 alone in one of two sexes, which are precisely alike 

 as regards heredity. Mimicry seems to be intimately 

 connected with the well-being of the mimicking 

 species, with its preservation, its direct advantage in 

 the struggle for existence. 



Mimicry in the female is of essentially the same 

 nature, and due to the same cause as the fact of the 

 frequently duller tints of female butterflies as com- 

 pared with the males. The circumstance of the highly 

 specialised forms of protec- 

 tive resemblance to inani- 

 mate objects in the females 

 of other orders, whose males 

 show only a very rude 

 approximation, bears the 

 same interpretation. The 

 female is the sex that is 

 disguised. She assumes the 

 general quiet tints of nature, 



or she adopts the exact colour and form of a 

 particular vegetative or mineral substance, or as in 

 Mimicry she becomes conspicuous enough, but is in 

 complete superficial resemblance to some other and 



FIG. 55. The larva of Puss Moth 

 in its terrifying altitude ; from 

 Trans. Entom. Soc. 



