THE GRASSHOPPER'S COUSINS 



wing on top and use the file of this wing and the scraper 

 of the left, just the reverse of the custom among the 

 katydids. 



The front wings of male crickets are usually very broad 

 and have the outer edges turned down in a wide flap that 

 folds over the sides of the body when the wings are closed. 

 The wings of the females are simpler and usually smaller. 

 The differences between the front wings in the male and 

 the female of one of the tree crickets (Fig. 37) is shown 

 at B and D of Figure 23- The inner half of the wing (or 

 the rear half when the wing is extended) is very large in the 

 male (D) and has only a few veins, which brace or stiffen 

 the wide membranous vibratory area or tympanum. The 

 inner basal part, or anal area, of the male wing is also 

 larger than in the female and contains a prominent vein 

 {Cu-i) which makes a sharp curve toward the edge of the 

 wing. This vein has the stridulating file on its under sur- 

 face. The veins in the wing of an 

 adult female (B) are comparatively 

 simple, and those of a young female (A) 

 are more so. But the complicated 

 venation of the male wing has been de- 

 veloped from the simple type of the 

 female, which is that common to in- 

 sects in general. The wing of a young 

 male (C) is not so different from that 

 of a young female (A) but that the cor- 

 responding veins can be identified, as 

 shown by the lettering. Taking next 

 the wing of the adult male (D), it is an 

 easy matter to determine which veins 

 have been distorted to produce the 

 stridulating apparatus. When the tree 

 crickets sing they elevate the wings above the back like 

 two broad fans (Figs. 37, 40) and move them sidewise so 

 that the file of the right rubs over the scraper of the 

 left. 



Fig. 34. A mole cricket, 

 Neocurtilla hexadactyla 



[57] 



