Home, and Range East of Mountains. 



61 



pamphlet already referred to, says that " north of the 

 49th parallel, the whole area of the third or highest 

 prairie-plateau, and probably much of the second, are 

 congenial breeding places, and here the locusts are always 

 in greater or less numbers." Regarding the western 

 boundary, nothing struck Prof. Thomas* as more singular 

 than the few specimens of spretus collected west of the 

 mountain range by the Hayden Geological Survey, from 

 which he infers that the line of the survey was along the 

 southwest border of its district. Mr. J. D. Putnam, of 

 Davenport, Iowa, who spent July, August and September 

 of 1875, in Utah, also informs me that he did not meet 

 with a single specimen. 



That the native home of the species is what naturalists 

 understand as sub-alpine, is rendered pretty certain, also, 

 by the fact of its abounding to such an extent in British 

 America, and of its breeding in the higher mountain ele- 

 vations, even up to the perennial snows. In fact, so high 

 up does it breed that it often hatches so late in the season 

 as to be overtaken by the cold of the succeeding winter 

 before acquiring growth, when of course it perishes with- 

 out begetting. The truly alpine country can not, therefore, 

 be its native home ; and those found breeding at such a 

 height must be the progeny of others which flew from the 

 plains, either east or west of the mountains. Physical 

 barriers on the high mountain summits put a limit to the 

 insect's extension and propagation, just as they do in the 

 Mississippi Valley. 



* Preface to his Report upon the Collections of Orthoptera made in Nevada, 

 Utah, California, Colorado, New Mexico, and Arizona, in 1871, 1872, 1873, and 

 1874, by Hayden'e Geol. Surv. of the Terr. (1876). 



