FIELD CROP INSECTS 



241 



Extensive experiments in the use of fungous diseases 

 for the control of the chinch-bug were conducted for many 

 years, but have resulted in proving the impracticability of 

 their artificial use. 



Where chinch-bugs are abundant the farmer should pre- 

 pare to devote himself and as many hands as necessary to 

 fighting them promptly if he would check their migration and 

 save his corn crop, for delay may mean ruin. 



139. Grasshoppers * (40d). Almost every year in some 

 part of the country crops are destroyed by hordes of hungry 

 grasshoppers, or locusts, as 

 they are called in Europe. 

 In the '70's vast areas in the 

 Mississippi Valley were dev- 

 astated by the clouds of 

 Rocky Mountain Locusts 

 which migrated down from 

 the table lands of the Rocky 

 Mountain region, but in 

 recent years this species has 

 practically disappeared from 

 the United States. Several 

 species are commonly de- 

 structive throughout the country. One of the most com- 

 mon is the -small Red-legged Locust,^ which is found in 

 almost every meadow. Very similar in both size and ap- 

 pearance is the Lesser Migratory Locust, \ so-called on ac- 

 count of its flying in large numbers from one point to another. 

 Another similar and closely related species is the California 

 Devastating Locust, which has usually been the most de- 



* Family Acrididce, see page 48. 



t Mclanoplus femur-rubrum Har. 



t Melanoplus atlanis Riley. 



Melanoplus devastator Scud. 



FIG. 166. Rocky Mountain locust; 

 adult and different stages of 

 growth of young. (After Riley. ) 



