April, '12] GILLETTE: GRASSHOPPERS IN COLORADO 121 



three-striped species, and this ditl great injury in certain parts of the 

 State in alfalfa fields, occurring there in swarms and extending over 

 square rods until the alfalfa was simply loaded down with them, and 

 they often destroyed large portions of the field. Westward, the spotted 

 species and one other predominated. We found the conditions very 

 similar to those described by Professor Washburn. We have not 

 experimented as yet with the sodium-arsenite treatment. We shall 

 do that next year. But we did work very thoroughly with poisoned 

 bran mash, using Paris green as the arsenical constituent, and found 

 it very satisfactory in most cases. 



GRASSHOPPER CONDITIONS IN COLORADO 



By C. P. Gillette 



This paper is in no true sense a discussion of the paper by Professor 

 Washburn but rather a companion article setting forth the grass- 

 hopper conditions in Colorado. 



During the summer of 1910, northern Colorado experienced the 

 worst grasshopper outbreak that I have witnessed since coming to 

 the State over twenty years ago. The grasshoppers that were most 

 abundant were, Melanoplus bivittatus, M. differentialis, M. atlanis 

 and M. femur-ruhrum, and in about the order named. It was the 

 first year that I have ever known differentialis to be as abundant in 

 northern Colorado as bivittatus, which is nearly always our most destruc- 

 tive species. 



The crops suffering most from the attacks of grasshoppers in Colo- 

 rado have been alfalfa, grain crops, sugar beets, potatoes, and garden 

 crops. There is no doubt but what the injury to the alfalfa exceeds 

 that of all of the other crops combined. It is common for the farmers 

 in northern Colorado to cut three crops of alfalfa each summer. In 

 the worst infested sections during 1910, only two crops were harvested 

 and the second of these did not exceed one-half of an ordinary crop. 



As a result of the severe injuries during 1910, a bill was framed 

 which passed the 18th General Assembly with scarcely a dissenting 

 vote, providing means for the control of farm pests, including grass- 

 hoppers and other injurious insects, rodents, weeds, and plant diseases. 

 The bill is commonly known as the Pest Law and provides for the 

 organization of districts, not to exceed thirty-six square miles in extent, 

 where at least fifty-one per cent of the property is owned by holders 

 who have petitioned for the formation of the district and who have 

 designated someone to act as inspector in the district and who also 

 is expected to enforce regulations that are furnished by the State 



