60 



The Rocky Mountain Locust. 



Omaha to Denver, collecting plants and capturing insects 

 along the route on every occasion ; I have traveled exten- 

 sively in Kansas, Indian Territory and Texas, always 

 collecting ; I have been overwhelmed in the latter State 

 with swarms of locusts while in front of an engine, and 

 yet, among all the locusts collected, I have never found 

 the genuine spretus, except as it came from the west or 

 northwest, or hatched from eggs laid by those which had 

 thence come. It can not be found there any more than it 

 can be found in the western counties of Missouri, except 

 as the progeny of invading swarms. There is no instance 

 on record of the species, when hatching out in any of this 

 country, remaining long enough to lay eggs, even suppos- 

 ing it capable of doing so in such circumstances. We 

 find it multiplying continuously west and north of the 

 boundary indicated ; pushing annually, in detachments, 

 eastward from the mountains to the west, and southeast- 

 ward from the country to the northwest; but only at long 

 intervals does it sweep down in countless myriads and in 

 extended and devastating swarms from the extreme north- 

 west. Just beyond the confines of the country in which 

 it permanently multiplies, it follows that it will more 

 often do injury than farther east and south ; it will also 

 hold its own longer, but sooner or later it vanishes from 

 the country beyond those confines. It either vacates the 

 territory on the wing, or is destroyed by influences adverse 

 to its well-being. 



In placing these confines along the 44th parallel and the 

 100th meridian, I think I have given the utmost southern 

 and eastern limits. It is even doubtful whether the- spe- 

 cies permanently multiplies in much of the country for 

 some degrees north and west of the territory thus indi- 

 cated. Prof. Thomas indicates the eastern boundary as 

 along the 103rd meridian, while Mr. G. M. Dawson, in the 



