N0.1124. nEnsiOX OF THE MET.AyOPLI—fiCrDhKU. 1)^7 



a fonrtli as \{\\\^ as the supiaanal platt': cerci forming nearly tiat plates, 

 about lialf as long again as broad, lying in a nearly unitbrin subver- 

 tical plane, generally slightly i*urve<l or bent upward, the apical half 

 slightly more «'onipresse<l than the basal and narrowed by a consider- 

 able oblique excision of the inferior margin, the X'\\^ broadly rounded 

 or subtruncate: sp.bgenital plate roundly subpyramidal, the ajucal mar- 

 gin with moderate abruptness, somewhat elevated, thickened, and 

 iiiesiallv n<>tclMMl distinctly. 



Length of body, male, 1*5 mm., female. 28 mm.; antennae, male, 1> mm., 

 female, S.7r» mm.; tegmina. male, 20.5 mm., female. 27.5 mm.; hind 

 femora, male and female, 14 nnn. 



Twohundred and seventy-six nniles, i30females. I refrain from giving 

 in detail the localities from which 1 hav e seen specimens, both on account 

 of their number .md because, from the irregular distribution of the 

 insect in different years, such details would have little value without 

 dates, which are not always accessible: farther on, however, I give all 

 that are of special interest. 



The name of this species is to be credited to ^l\\ V. W. Thler, who 

 )>laced it in his collection thirty or more years ago and communicated 

 it to various persons, who used it. sometimes in an incorrect form. The 

 original siJecimens were received from Mr. Kobert Kennicott, and were 

 obtained by him from a migratory horde which settled in the then Red 

 INver settlements, now Winnipeg and vicinity, Manitoba. On Mr. 

 rider's generous transfer of his collection to me, these specimens, with 

 their history, came into my possession, and I now have them with his 

 (•riginal labels. One has been placed in the National Museum. 



It was thus known from the start as a migratory insect, and com- 

 paring it with any species of the genus one would at once be struck 

 with the greater length of the tegmina and wings. These were meas- 

 ured bv liilev; in fortv-eight males the tegmina extended bevond the 

 abdomen 5 to 10 mm., with an average of 7.0 mm. : in ninetj'-nine females 

 they ranged from •'» to 10 mm. beyond the abdomen, the average (».7 mm. 



It is now well known as the "Kocky Mountain Locust " or destructive 

 locust of the States in the western half of the ^Mississippi Valley. It 

 has beeu njore written about than any other American Orthopteron, and 

 was specially discussed by the Tuited States Entomological Conunission, 

 organized to devise methods of checking its ravages after a study of its 

 natural history. It forms thp almost exclusive subject of their tirst 

 report, and occupies a considerable space m their second. AlthougU a 

 considerable body ot the evidence adduced by them is contradictory 

 and in part of doubtful application to this ])articular species, their con- 

 clnsiojiis are in very large measure well founded. As ai)pears from a 

 study of their work and other available material, the following conclu- 

 sions mav be fairlv drawn : 



(1) Th(i home of the species is in favorable localities in the elevated 

 region of the Ilocky Mountains or immediately boroering it from the 



