62 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



important part of the Permanent Region, but it is not clear how- 

 important a part. Walker (1910, p. 336) summarized distributional 

 findings of the U. S. Entomological Commission for Canada, so far as 

 the "Regions" were concerned, but he added little new information. 

 Criddle (1917), perhaps basing an opinion on observations during years 

 long after the main outbreak period, said that "invasions of Canada" 

 occurred only during dry seasons, the swarms arriving in July and 

 August. Roe (1951), in his discussion of the buffalo, said that in the 

 1870's and 1880's there was quite common ignorance of western 

 Canada. It may have been easy to ascribe the source of something 

 poorly understood (i. e., swarms of spretus) to a vast, distant region 

 that was little known entomologically. 



Within the Permanent Region, spretus did not breed everywhere, 

 but instead it did so in favorable spots. River bottoms, sunny slopes 

 of uplands, and subalpine grassy areas among the mountains were 

 considered to be favored egg-laying sites. After maturity was 

 reached, flights within the Permanent Region were common. More 

 devastating and consequently much more widely publicized, however, 

 were the "invading swarms" which w^ent primarily in a southerly 

 or southeasterly direction (except when west of the Rocky Moun- 

 tains), A day's flight was estimated to be from 20 to 150 miles. 

 Stops w^ere usually made at night, but not always. Diu-ing brief 

 stops, or when settled in an area for egg-laying, the swarms ate nearly 

 all crops and wald plants. Sw^arms might stop anywhere in the 

 Temporary Region. Riley (1877b, p. 95) stated that in 1876 swarms 

 left Montana about the middle of July and reached Texas by the 

 end of September, thus covering 1,500 miles in 75 days, an average 

 of 20 miles per day. 



Swarms developing from eggs laid in the Temporary Region usually 

 migrated northward or northwestward. In the southern part of the 

 infested area a partial second generation sometimes occurred, but 

 spretus had essentially a single generation per year. The time of 

 hatching, as a general rule, varied from the middle to end of March 

 in Texas, to the middle of May or beginning of June in Montana. 

 The yoimg grasshoppers typically displayed gregarious habits soon 

 after hatching and initial feeding near the hatching site. The nymphs 

 were described as moving in "schools or armies," generally "marching 

 in a given direction until toward evening" (Riley, 1891, p. 21). 

 Sometimes the nymphs migrated in a band a mUe wide across the 

 front (Riley, 1877b, p. 233). Usually, marching occurred only during 

 the warm hours of the day. 



Melanoplus spretus was considered to be nearly omnivorous on both 

 native and cultivated plants, with vegetables and cereals a "main- 

 stay," though at least in some instances sorghum and broom corn 



