CHAPTER V 



INSECTS 



Lepidoptera Mimicry. The subject of mimicry is con- 

 nected with the subject of sexual dimorphism very inti- 

 mately by the fact that in a certain number of cases the 

 difference between the sexes in Lepidoptera is that one 

 sex mimics some species of a remote group, while the other 

 preserves the usual characteristics of its family. This fact 

 is mentioned and discussed by Darwin. He remarks that 

 in such cases it is obvious that the successive variations 

 by which one sex, e.g. the female, has been modified have 

 been transmitted to her alone. He suggests that some 

 of the variations have been at times transmitted to males, 

 but that such males have been eliminated by being thus 

 rendered less attractive to the females. He supposes, that is 

 to say, that the females while undergoing modifications of 

 colour themselves, in a certain direction, would have nothing 

 to do with males that varied in the same direction. In 

 support of this suggestion he quotes some sentences from 

 Mr. Belt concerning the retention, in the males of some species 

 of mimicking Leptalides, of an original or Leptalid character 

 which is wanting in the female. In one case such a character 

 is a white patch on the wing, which Belt imagines to be 

 exhibited to the females in courtship to gratify " their deep- 



