INJURING THE LEAVES. 



249 



Fig. 135. Rocky Mountain Locust : 

 a, b, young nymphs ; c, fully de- 

 veloped nyrnph or pupa ; d, adult. 



finally become full-fledged (d). They are active 



during their entire ex- 

 istence. The native 

 home of this species is 

 in the high and dry ta- 

 ble lands of the Rocky 

 Mountain regions, where 

 it breeds year after year. 

 Occasionally it becomes 

 so abundant in these re- 

 gions that the food sup- 

 ply is exhausted, and it 

 is compelled to seek by flight green pastures. It is 

 at such times that these insects migrate in vast 

 swarms to the fertile fields of the Mississippi Valley, 

 destroying every vestige of greenness in their path. 

 Fortunately, however, they are unable to breed per- 

 manently at these lower levels, and although eggs 

 are deposited by these invading hordes, the young 

 hoppers hatched from them seldom attain a healthy 

 development. 



The commonest grasshopper in the Northern 

 States is called the Red-legged Locust (Mclanoplus 

 femur-rubrum). It is closely allied and very similar 

 to the Rocky Mountain Locust. It frequently be- 

 comes seriously destructive in restricted localities, 

 but never does the wide-spread damage of its West- 

 ern congener. The life-history of this species has 

 been summarized by Professor S. A. Forbes as fol- 

 lows : " These locusts are single-brooded ; they hiber- 

 nate in the egg, hatching in midsummer; pass 



