2 BULLETIN 967, U. S. DEPARTMENT OF AGRICULTURE. 



while entomologist of Missouri, to work out the first life histories of 

 ^American species, and later as a member of the U. S. Entomological 

 Commission to extend his researches in this line. Riley studied only 

 species of general occurrence and only two of them to completion, yet 

 he announced as his opinion that the life histories of other species 

 would be found strictly parallel to these. 



With the subsidence of outbreaks of the Rocky Mountain grass- 

 hopper (31 elano plus spretus Uhler), the Commission directed its 

 attention to the more pressing problems of thickly settled portions 

 of the country. The writer knows of no further study of the eco- 

 nomic relations or biology of American species of this group. 



The data on blister beetles that form the basis of this bulletin 

 were collected, except as otherwise specified, since 1913. From 

 March. 1913, to May, 1915, inclusive, the work was conducted at 

 Garden City, Kans. From June. 1915. to June. 1917. inclusive, it- 

 was continued at Wichita. Kans. As the beetles do not occur there in 

 sufficient numbers to supply the necessary material, work on con- 

 trol measures was dropped, and only such life-history work was con- 

 ducted as was possible with material collected on infrequent trips 

 at irregular intervals to western Kansas. 



ECONOMIC IMPORTANCE. 



There has been a tendency among entomologists to class the west- 

 ern species of blister beetles as beneficial. This arises from the fact 

 that their larvae feed on the eggs of grasshoppers, from the ravages 

 of which the early agriculture of the plains region suffered im- 

 mensely. However, the species of grasshopper responsible for a 

 large share of the injury, and the one that stands to-day an insect 

 bogy to those of limited entomological knowledge, has disappeared 

 from the scenes of its former activity so completely that specimens 

 of it are curiosities to the new generation of entomologists. 



Only since the agricultural possibilities of the semiarid regions 

 have been developed along diverse lines has it been possible to form 

 a true estimate of the economic status of blister beetles. The pres- 

 ence of extensive acreages of sugar beet, alfalfa, beans, and peanuts 

 has allowed them to exhibit to the full their propensity as crop de- 

 stroyers. The cultivation of large areas and the close pasturage of 

 a great deal more have also altered the flora and environment to 

 such an extent that the former equilibrium of the insect fauna has 

 been disturbed. Cultivation has insured a much more extensive 

 food supply for grasshoppers, and they have become distributed ac- 

 cordingly: but much of this increase in the food of grasshoppers 

 has not been accompanied by a corresponding increase in food suit- 

 able for the adult blister beetles. The latter have, therefore, been 



