﻿OF THE STATE ENTOMOLOGIST. 163 



seldom, if ever, gets soaked with moisture. Prof. Thomas found it 

 most numerous in all stages of growth along the higher valleys and 

 canyons of Colorado, tracing it up above the perennial snows, where 

 the insect must have hatched, as it was found in the adolescent stage. 

 In crossing the mountains in Colorado it often gets chilled in passing 

 the snows, and thus perishes in immense numbers, when bears delight 

 to feast upon it. 



My own belief is that the insect is at home in the higher altitudes 

 of Utah, Idaho, Colorado, Wyoming, Montana, Northwest Dakota and 

 British America. It breeds in all this region, but particularly on the 

 vast hot and dry plains and plateaus of the last named Territories and 

 on the plains west of the mountains ; its range being bounded, perhaps, 

 on the East by that of the Buffalo grass. Mr. Wm. N. Byers, of Denver, 

 Colorado, shows that they hatch in immense quantities in the valleys of 

 the three forks of the Missouri river and along the Yellosv Stone, and 

 how they move on from there, when fledged, in a southeast direction 

 at about 10 miles per day. The swarms of 1867 were traced, as he 

 states, from their hatching grounds in West Dakota and Montana, 

 along the east Hank of the Rocky Mountains, in the valleys and plains 

 of the Black Hills, and between them and the main Rocky Mountain 

 range.* 



In all this immense stretch of country, as is well known, there are 

 immense tracts of barren, almost desert land, while other tracts for 

 hundreds of miles bear only a scanty vegetation, the short buffalo 

 grass of the more fertile prairies giving way, now to a more luxurious 

 vegetation along the water courses, now to the sage bush and a few 

 cacti. Another physical peculiarity is found in the fact that while 

 the Spring on these immense plains often opens as early, even away 

 up into British America, as it does with us in the latitude of St. Louis, 

 yet the vegetation is often dried and actually burned out before 

 the first of July, so that not a green thing is to be found. Our Rocky 

 Mountain Locust, therefore, hatching out in untold myriads in the 

 hot sandy plains, five or six thousand feet above the sea level, will 

 often perish in immense numbers if the scant vegetation of its native 

 home dries up before it acquires wings ; but if the season is propi- 

 tious and the insect becomes fledged before its food supply is ex- 

 hausted, the newly acquired wings prove its salvation. It may also 

 become periodically so prodigiously multiplied in its native breeding 

 place that, even in favorable seasons, everything green is devoured 

 by the time it becomes winged. 



•See Haydeh's Geol. Survey of the Territories, 1870, pp. 282-3. 



