134 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



Cache Yalleys have been annually more or less devastated. The swarms 

 have invariably originated in the region to the north, in the valley of 

 the Gallatin, Madison, and Jefferson Rivers. The area extends south- 

 ward to Salt Lake City. The remaining portion of Utah is more or less 

 barren, dry, and sandy, affording no pasturage sufficient to yield food to 

 large numbers of locusts, or grasshoppers of any sort. Nearly all that 

 visit the Salt Lake Yalley come from the Bear Eiver, Cache and Malade 

 Yalleys, while a few probably originate in the region east of the Wah- 

 satch Mountains, and some may fly over from Western Colorado. 



The State of Nevada affords no feeding grounds for the locust, for 

 the same reason that they do not breed in the greater part of Utah, viz, 

 the hot, dry, barren soil affording no grassy plains or fertile river-bot- 

 toms for the maintenance of extensive swarms of locusts, except in the 

 Viilley of the Owyhee River, a limited tract in Northeastern Nevada. 

 For the same reason Arizona and New Mexico are not the permanent 

 abode of the Rocky Mountain locust. 



A large and important area remains to be described, viz, that watered 

 by the upper North Platte River and its tributaries, especiallj^ that por- 

 tion of the Platte called the Sweetwater River, east of the 104th meri- 

 dian. This area also includes the plains and valleys lying north and 

 south of the Union Pacific Railroad, the valley of the South Platte west 

 of longitude 105^ 30', and the upper Arkansas River, west of the same 

 meridian. West of the Rocky Mountain Range the area probably in- 

 cludes the head-waters of the Yampah or Bear, the Snake and Green 

 River Yalleys, north of the 41st parallel. South of this parallel the 

 region, which with our present information on a map of this size can be 

 only approximately drawn, includes the Rocky Mountain Range. In this 

 range the permanent breeding grounds are restricted mainly to the ele- 

 vated (8,000 or 9,000 feet) North, ^Middle, and South Parks, and to valleys 

 lying below them, as well as to the areas more favorable to the propaga- 

 tion of the grasshopper lying among the foot-hills of the Rocky Moun- 

 tains and the plains immediately adjacent. As a matter of fact, the 

 farming regions lying near the range, as at Greeley, Denver, and the 

 neighboring towns, are exposed to visitations in those years when the 

 locusts multiply unduly in the permanent area, and it is doubtful just 

 where the line between the loot-hills and plains in which these towns 

 are situated should be drawn. Without much doubt, most of the swarms 

 which devastate the fiirmiug portion of Colorado aie mostly foreign to 

 the Stale, and originate in Wyoming ; while a few, sometimes, however, 

 large and destructive, fly over the range from Western Colorado. 



In conclusion, it will be seen that the areas marked on the map as 

 forming the native or permanent breeding grounds of the Rocky Moun- 

 tain locust comprise nearly all the available farming regions in the im- 

 mense area of the United States lying between the 104th and 120th 

 meridians. We shall be compelled to look squarely in the face the un- 

 pleasant lact that the sections in this area best adapted to agriculture, 



