GRASSHOPPERS AND THEIR RELATIFES 



317 



for its large size and its powers of flight. There are 

 many species of these large locusts, which migrate in 



From Brehm's " Thierleben' 

 FIG. 113. The migratory locust of the Old World (Pachytylus migratorius). 



vast swarms and sometimes are met with at sea, Rocky 

 hundreds of miles from land. The Rocky Mountain 

 locust, on the other hand, is a relatively small insect, 

 which when observed singly would always be regarded 

 as a mere grasshopper. In former times this species 

 used to migrate in incredible numbers, utterly de- 

 stroying the crops. It is improbable that such great 

 plagues of grasshoppers will ever again occur in our 

 country; for the territory in which they bred has been 

 mainly turned into farms, and the plowing of the land 

 destroys the eggs. Our abundant and troublesome 

 grasshoppers today are almost entirely resident or 

 nonmigratory forms, and these will be diminished in 

 number as more land passes into cultivation. 



