PRACHEATA 339 
damage. One species, Acridiwm migratorium, which is found 
all over Europe and Asia, moves as a locust swarm, and devours 
every green thing which it comes across. 
Fria. 190.—Acridium peregrinum. Natural size. 
Some species attain a large size, measuring four or six 
inches in length. 
2. Locustidae.—The Locusts are usually of a green or 
brown colour; they have long filiform antennae, and their 
wings lie vertically along the side of the body. The auditory 
organ is situated upon the tibiae of the anterior pair of legs ; 
the tarsus is four-jointed. The female bears a pair of long, 
sabre-like processes which form the ovipositor; this bores into 
the ground, and the eggs are deposited by it. The stridulating 
noise of the male is caused by drawing the rough vein of the 
left anterior wing over a file-like structure situated on a vibrat- 
ing membrane at the base of the right. 
