41 8 THE WONDER OF LIFE 



tussocks of grass, where they are very inconspicuous. The 

 males are able to produce a cracMing or snapping sound, 

 and it seems as if the females responded to this signal by 

 vibrations of their body and wings. When the males 

 fly overhead or settle down in the vicinity, the females 

 make themselves more conspicuous by their tremulous 

 movements, which appear to attract the male's attention. 

 When the sound stops, the answering movement stops. 

 Even when the female cannot see the male, she answers 

 back when the sound begins. It seems, then, as if the male's 

 signal appealed to a hearing organ and the female's signal 

 to sight. Dr. Peters's observations are of great interest, 

 because the experiments that have been made to test the 

 auditory powers of insects have been very unsatisfactory. 

 It is difficult to beheve that the instrumental music of 

 Cicadas and crickets falls on deaf ears, but the experiments 

 testing this are inconclusive. Insects that have been 

 credited with the power of hearing remain quite indifferent 

 to a great variety of sounds, but it is possible that the 

 experiments fail because the sounds used as tests have 

 been meaningless and therefore quite uninteresting to the 

 insects. More observations hke those of Dr. Peters are 

 much to be desired. 



Puzzles of Behaviour. — The Praying Mantis, or Prego- 

 Dieu of the Proven9als, is a ferocious Carnivore in a vege- 

 tarian order (Orthoptera), and feeds exclusively on living 

 victims, such as crickets, which it seizes by the back of the 

 neck. Fabre has shown that in comfortable captivity, 

 with abundant food, the mature females fight fiercely 

 and devour one another. The males Hkewise, smaller 

 and more delicate than the females, are often devoured 

 by their mates, after having had their addresses accepted. 



