128 SEX 



there are many sounds to which insects 

 credited with hearing pay no attention what- 

 soever. Perhaps these sounds were not of the 

 sort to which insects' ears are attuned, and 

 Dr. Karl Peters suggests that the experi- 

 ments which have yielded negative results 

 have been too much restricted to sounds 

 that have no biological significance to the 

 creatures experimented with. He has, him- 

 self, made careful observations on a case 

 which strongly suggests that there may be 

 hearing in the strict sense, and that the 

 production of sound may be utilised in insect- 

 courtship. 



Peters's observations relate to an Alpine 

 moth which is abundant at Arolla, at a height 

 of about 2500 metres. The males fly about 

 actively; the females are sluggish, and sit 

 mostly on the tussocks of grass, where they 

 are very inconspicuous. The males are 

 able to produce a cracking noise, which is 

 peculiar to them, and the females respond to 

 this, even when it is impossible for them to 

 see the males, by vibrating their body and 

 wings. The reaction on the female's part 

 begins when the male flies past overhead or 

 settles down close by ; it stops when the sound 

 stops. It seems difficult to avoid the con- 

 clusion that the female hears the male's love- 

 signal. It seems likely that sight plays a 

 r61e on his part, and that the tremulous, 

 vibrating movements of the female attract 

 his attention. 



We cannot say more in regard to this 

 fascinating subject of animal courtship. In 

 a great variety of ways, male animals seem to 



