GRASSHOPPERS — GURNET AND BROOKS 63 



were left untouched (Riley, et al. 1878, p. 251). No thorough analysis 

 of preferences among the native food plants of the Permanent Region 

 seems to have been made, leading Pfadt (1949, p. 39) to conclude 

 that there is no information concerning the food-plants on which 

 spretus originally developed. 



During the years when it was more or less prevalent, spretus varied 

 considerably in its abundance and destructiveness. Riley (1891, p. 

 10) gave a resume of the relative abundance between 1818 and 1888. 

 Bethune (1875) briefly described the early destructive outbreaks in 

 Manitoba, and a recent summary is by Mitchener (1954). Some of 

 the summaries of experience with grasshoppers in various States, such 

 as that of Smith (1954) for Kansas and of Munro (1949) for North 

 Dakota, have not always differentiated between various species, as 

 of course it is impossible to do for many of the early years. Schle- 

 becker (1953) has given perspective to the general subject of grass- 

 hopper outbreaks, and has reviewed the period of great damage by 

 spretus. The year 1866, when the Rocky Mountain grasshopper did 

 great damage in Kansas, Nebraska, northwestern Texas, and also 

 invaded western Missouri, is described as one of the first years in 

 which it attracted national attention. The years of greatest abun- 

 dance were 1873-1876, with 1874 the high point in destructiveness. 

 In 1874, Colorado, Nebraska, and Kansas were overrun, and parts of 

 Wyoming, the Dakotas, Minnesota, Iowa, Missouri, New Mexico, 

 Oklahoma, and Texas were ravaged by swarms from Montana and 

 Canada where they were abundant (Riley, 1891). As recorded by 

 RUey, et al. (1880), and recalled by Bruner (1883), infestations 

 dwindled in 1877. Widespread abundance of spretus never occurred 

 again, though some injury in various years of the 1880's is attributed 

 to it, including an important local outbreak in Otter Tail Co., Minn., 

 in 1888. None of the 1888 specimens is preserved, so far as known 

 (Hebard, 1932b, p. 37). Riley, et al. (1883), mapped the reported 

 hatching and flights of 1880 and 1881. Bruner (1893) reported 

 spretus present in many parts of middle and eastern Nebraska in 1892, 

 and quite common at Lincoln, Nebr. 



It is probable that the layers of spretus in Grasshopper Glacier, 

 Park Co., Mont., were deposited during the major recorded swarming 

 years for spretus, or in earlier years that were comparable, though not 

 recorded. This glacier, located near the northeastern corner of 

 Yellowstone National Park, has been discussed in detail by Gurney 

 (1953). Flights of grasshoppers, probably aided by favorable air 

 currents, occasionally pass over the glacier, even at its altitude of 

 nearly 11,000 feet, and specimens landing on the snow are preserved 

 when the necessary subsequent conditions of freezing and snowfall 

 occur. Several species have been collected alive on the snow of the 



