SECONDARY SEXUAL CHARACTERS 117 



males with female wings as readily as they accepted 

 normal males. 



In the gipsy moth (Porthetria dispar), the male is 

 brown and the female white (Fig. 60). Here again 

 it was found that the males are guided solely by the 

 odor of the female. 



The silkworm moth is also sexually dimorphic. Kel- 

 logg has shown that males with blackened eyes find a 

 female with as much precision as does a moth with 

 normal eyes. 



If the antennae are cut off, however, the male can not 

 find the female unless by accident he touches her. He 

 then mates. The female has scent glands whose odor 

 excites the male with normal antennae even at some dis- 

 tance. Chemotaxis and contact are the active agents 

 in mating. The eyes do little or nothing. 



Andrews has found that touch determines mating in 

 the crayfish. Pearse has obtained similar results. 

 Chidester has shown the same thing for crabs. Holmes 

 found this kind of behavior in Amphipoda. Fielde and 

 Wheeler have also found that in ants sex-discrimination 

 is through smell or by what Forel calls contact-odors. 



Montgomery and Porter recognize touch as the most 

 important factor in mating in spiders. Petrunke- 

 witsch has shown that in the hunting spider vision also 

 helps the sexes to find each other. Tower has found 

 that contact or odor rather than sight is the important 

 condition in mating in leptinotarsa. 



I am able to give the unpublished results of A. H. 

 Sturtevant on the mating of the fruit fly, drosophila. 

 The male carries on an elaborate courtship in the 

 sense that he circles around the female, throws out one 



