382 



CHARACTERS OF INVERTEBRATE ANIMALS 



while the very smallest are included in the genus Tettix. The 

 characteristic chirping is produced by rubbing the inner side of the 

 hind-legs against the outer surface of the front wings, the former 

 being provided with a ridge made up of small peg-like projec- 

 tions. The sounds audible to human ears are produced only by 

 the male. 



What are popularly known as " locusts " are simply species 

 of grasshopper, which from time to time appear in swarms 



Fig. 231. — Migratory Grasshopper — "Locust" {AcridiuTtt peregrinum^ 



which migrate from place to place and do a vast amount of 

 damage. The best-known species is the European migratory 

 locust, which ranges from China to the Atlantic. A large species 

 {Acridium peregrinuni) (fig. 231), common in North Africa, is 

 probably the locust mentioned in the book of Exodus. 



Green Grasshoppers are easily distinguished from the members 

 of the preceding group by their extremely long and slender an- 

 tennae. There are generally auditory organs situated in the front 

 legs just below the knee. Chirping organs, when present, are 

 placed on the bases of the fore-wings, the left carrying a 

 roughened edge (file) and the latter a sharp edge. In most 

 species the female possesses a long egg-laying tube or ovipositor. 



