ORTHOPTERA. 333 



The Leaping Orthoptera have the thighs and 

 shanks of the hindmost legs greatly developed, by 

 the muscular power of which they are enabled to 

 perform vast leaps. The males produce a ringing, 

 chirping sound, which is caused by the rubbing of 

 the thighs against the edges of the elytra, or by the 

 friction of one elytron upon the other. No insect 

 has a true voice. In the House Cricket (Gryllus* 

 Domesticus) this chirping is often annoying from its 

 pertinacity, though some persons think it agreeable. 

 The most remarkable of this family are the Migratory 

 Locusts, (Acrydium^-) several species of which, agree- 

 ing in manners, but inhabiting different regions, ap- 

 pear to have been confounded. The immense armies 

 which occasionally overrun Eastern countries, sha- 

 dowing the sun ; and the devastation they produce, 

 eating up every green herb, and leaving the land 

 as if a fire had passed over it, are familiar to all, 

 from the frequent allusions to them in the Sacred 

 Writers, as well as from the descriptions of Oriental 

 travellers.}; 



* Ff vAA, gryllizo, to creak. t 'Aa^/j, acm, a locust, 



f See Joel ii. 11 1. 



