ORTHOPTEBA 



87 



and rubbing together the two wing covers or outer wings 

 on the bases of which are roughened portions. The rate 

 of chirping is according to the temperature of the air. 



, chirps per minute 40 

 The formula, temperature = 50 H r 



will enable any one to know how high the mercury stands. 

 The sounds made 

 by the male locusts 

 are produced in 

 some species by rub- 

 bing the hind legs 

 against the outer 

 wings and in others 

 by rubbing together 

 the upper surface 

 of the front edge of 

 either hind wing and 

 the under surface 

 of a wing cover. All 

 the high shrill notes 

 of the upland heard 

 on dull days and in 

 the evening are pro- 

 duced by the crick- 

 ets, grasshoppers, or 

 locusts on whose legs 

 or wings the rough 



Surfaces OCCUr. The FIG. 12. Walking stick (JXapheromera femorata). 

 cricketfeedsOngraSS, Photograph, natural size. 



clover, or almost any other kind of vegetation. There are 

 numerous species of the cricket family (GrylUdce) . 



