SOUNDS OF INSECTS. 369 



Organs of hearing may be situated either on the fore legs, 

 as in the green grasshoppers, katydids, or at the base of 

 the abdomen, as in the locusts. Most Orthoptera have a 

 large ovipositor by which they burrow in the earth or into 

 soft wood, and deposit their eggs singly or in masses. 

 Mantis (Fig. 333) lays its eggs in a cocoon-like mass. 



Many Orthoptera, as the crickets, green grasshoppers, 

 katydids, etc., and locusts, produce loud, shrill sounds, 



Fipr. 333. An African Mantis, or soothsayer, with its egg-mass. From Monteiro's 

 Angola. 



which are sexual calls. They stridulate in three ways 

 i.e., first, by rubbing the base of one wing-cover on the 

 other (crickets and green grasshoppers) ; second, by rub- 

 bing the inner surface of the hind legs against the outer 

 surface of the front wings (some locusts) ; third, by rub- 

 bing together the upper surface of the front edge of the 

 hind wings and the under surface of the wing-covers during 

 flight (some locusts). 



