GRASSHOPPERS — GURNEY AND BROOKS 65 



the foremost American field student of grasshoppers of his time, of 

 factors of weather, natural enemies, and other influences thought to 

 be related to spretus abundance, but the enigma remains. Cantrall 

 and Young (1954) hinted at an influence by the American buffalo: 

 "It is obvious that any disturbance in a habitat is accompanied by 

 population fluctuations with the increase of some species and the 

 decrease of others. The appearance of the migratory locust, Melano- 

 plus mexicanus migratory phase spretus, following reduction of the 

 great buffalo herds may be a classical example of the phenomenon." 

 We have examined the well-documented reports of Hornaday (1889) 

 and Roe (1951) in an effort to determine whether there is a chrono- 

 logical correlation between the disappearance of the buffalo and the 

 abundance or disappearance of spretus. So far as the southern herd, 

 centered in Kansas and adjacent States, is concerned, the last hunting 

 on a large scale occmTed during the winter of 1875-1876. In 1871, 

 by which time much attention already had been attracted to the 

 migration of spretus, millions of buffalo remained in Kansas, Okla- 

 homa, and the Texas Panhandle. The northern herd, located mainly 

 in Wyoming, Montana, and the Dakotas, was slaughtered later than 

 the southern one. The years 1878-1883 were the biggest hunting 

 years, with the last major hunt in the season (about October-Febru- 

 ary) of 1882-1883. Therefore, in Montana, which was the heart of 

 the Permanent Region for sj^retus, the peak of grasshopper outbreaks 

 had passed (1877) before the buffalo herd was removed. After 

 considering possible effects of the buffalo in feeding and trampling on 

 the range, and the feeding by young nymphs on dry buffalo manure, 

 it is difficult to see any relation other than near chronological coinci- 

 dence between grasshopper and buffalo. 



Uvarov (1921) advanced the "phase theory" of locusts, which later 

 became generally accepted as a fact, and Hebard (1925a, pp. 112, 113; 

 1928, pp. 281-284) suggested that spretus might be the migratory 

 phase of mexicanus. Faure (1933) concluded, following rearing experi- 

 ments, that he had demonstrated that nymphs of bilituratus [mexi- 

 canus] could change into spretus, thus establishing the phase explana- 

 tion. However, the measurements of his laboratory-reared ''spretus" 

 are not fuUy typical of the historical specimens of spretus, and his 

 demonstration was not conclusive (Hebard, 1936c, p. 48). Brett 

 (1947) also believed that by regulating the food and laboratory 

 environment of growing nymphs he had produced "spretus." His 

 material, samples of which have been deposited in the U. S. National 

 Museum, shows considerable variation in wing length, but the aedeagi 

 of all the males seen are ascribable to M. bilituratus vulturnus, and 

 no approach to the aedeagus of spretus is shown. If spretus were a 



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