THE CLASSIFICATION OF INSECTS 163 



except in size and the absence of wings, have the same feeding 

 habits and the same haunts as the adults. The name of the 

 order is derived from the straight-margined parchment-like 

 fore wings (orthos, straight, and ptera, wings) which are chiefly 

 used as covers to protect the large membranous hind wings on 

 which the flight function depends. There are numerous wing- 

 less species in the order, and some with degenerate short wings 

 incapable of flight. 



The " music" which is made by the male 'crickets, katydids 

 and meadow-grasshoppers, is produced by the rubbing to- 

 gether of the bases of the f ore < wings in which certain veins 

 are thickened and roughened so as to make effective stridulat- 



FIG. 76. The American locust, Schistocerca americana. (Natural size.) 



ing organs. Grasshoppers make sounds when at rest by 

 rasping the inner surface of the broad hind legs across the 

 outer surface of the folded fore wings, and while in flight many 

 of them make a loud clacking sound by striking the front 

 margin of the hind wings back and forth past the hinder 

 margin of the thickened fore wings. 



Despite the beneficial feeding habits of the insect-preying 

 mantises, the Orthoptera as a whole must be looked on as a 

 seriously injurious group of insects. Cockroaches are great 

 pests in houses, while crickets and especially grasshoppers 

 work much injury to field crops. The notorious Rocky Moun- 



