INSECTS AFFECTING GRAINS, GRASSES, FORAGE 97 



frame buildings. Stories of their incredible appetites are legion; 

 a friend informs me that he still possesses a rawhide whip which 

 they had quite noticeably gnawed in a single night ! 



By mathematical computation it has been shown that such 

 a swarm could not reach a point over thirty miles from its 

 birthplace, and as a matter of fact they have never been known 

 to proceed over ten miles. 



FIG. 64. A swarm of grasshoppers attacking a wheat-field. (After Riley.) 



As the nymphs become full grown they are increasingly 

 subject to the attacks of predaceous birds and insects, insect 

 parasites, fungous and bacterial diseases, and are also largely 

 reduced by the cannibalistic appetites of their own numbers. 

 When the mature nymphs transform to adult grasshoppers and 

 thus become winged, large swarms are seen rising from the 

 fields and flying toward their native home in the Northwest. 



