THE LOCUST OR SHORT-HORNED GRASSHOPPER 365 



locusts there are two methods of stridulation. When at rest, 

 certain species draw the hind legs across the wing-covers in such a 

 manner that the ridges on the femoral joint of the legs are rasped 



Fig. 184. — Stridulating or chirping organs of katydid, Microcentrum 



iaurifoHum. 



A, dorsal aspect of file (ft) when the wing-covers are closed. B, ventral aspect of left 

 wing-cover to show file. C, dorsal aspect of right wing-cover to show scraper (s). In 

 the male the left wing-cover, which overlaps the right, bears a file-like ridge (st) while the 

 opposite wing-cover bears a scraper {s) at right angles to the file. The wing-covers are 

 first spread a little; then as they close gradually the scraper clicks across the teeth, making 

 from twenty to thirty sharp "tic "-like sounds in rapid succession. This call guides the 

 female to the male and when they are a few inches apart she makes now and then a short, 

 soft chirp, to which he responds with a similar chirp, which is quite unlike the first call 

 and, moreover, is made by the opening of the wing-covers. These and other details of the 

 courtship may readily be observed in twilight and even under artificial light, as the latter, 

 if not too strong, does not disturb the pair. (From Folsom, "Entomology," copyright, 

 1906, by P. Blakiston's Son & Co., reprinted by permission.) 



against a specialized vein of the wing-cover. Or, during flight, 

 they may rub the wings and wing-covers together, producing the 

 characteristic " clacking " sounds. A famihar example of another 



