MIGRATIONS IN WYOMING AND COLORADO. 157 



on the third map, which represent actual observations, involving no 

 theory, the fact that the flights are in the main from the northwest will 

 seem to be supported. While some swarms have been observed traveling 

 northward and northeastward, the great majority are reported to travel 

 eastor southeast. In 1873 immense numbers flew east through Bridger's 

 Pass. In 1875 vast numbers were observed at Laramie City flying south- 

 ward and southeastward. Previous to this year Mr. Thomas saw a 

 swarm flying at South Pass a little north of east, and another near Fort 

 Fetterman due east. In August, 1876, Lieutenant Carpenter, U. S. A., 

 and Mr. Strayhorn, saw swarms flying toward the southeast over a large 

 portion of Northeastern Wyoming, east of the Big Horn Mountains and 

 north of the Black Hills, which separated the swarms, the locusts flying 

 in a general southeast course on each side of that group of peaks. At 

 Laramie and Cheyenne the locusts nearly always come from the north- 

 west, and thence fly southward along the base of the Eocky Mountains, 

 passing over Denver. Lieutenant Carpenter is very ex[)licit in his state- 

 ments that no swarms fly directly south from the Black Hills into Colo- 

 rado, but that they fly directly southeast into Nebraska. 



In the Wind River Valley, in 1876, swarms were seen by Lieutenant 

 Carpenter flying southeast ; it would thus seem that probably over most 

 of Wyoming, in 1876, there was a general exodus of locusts toward the 

 the southeast into Nebraska and Kansas, as well as Colorado. 



In 1877, July 20, Lieutenant Carpenter observed in the Little Big 

 Horn Valley locusts flying in a northwest course into Montana. These 

 may have originated in extensive hatching-grounds noticed by him 

 about Fort Reno in the late summer of 1876. 



Colorado. — This State is so mountainous east of longitude 104° 30^ 

 that the movements of the locusts are uncertain and diiflcult to gener- 

 alize. As a rule the injurious swarms are su i)posed to come from the 

 north and northwest, and sometimes directly across the Kocky Mountain 

 Eauge from the Middle Park and the Snake and Bear Eiver Valleys. 



The observations in Colorado have mostly been made at or near Den- 

 ver, so that over most of the State the movements of swarms have uoc 

 been observed. 



In 1864 the destructive swarms came from the northwest. In 1867 

 a swarm from the west side of the range poured into Middle Park. In 

 1874 the swarms came from the north and west. The next year flights 

 of locusts visited Denver, presumably from the North Park, and at 

 Greeley they came from the north and northwest. Departing swarms 

 usually pass to the south and southeast, and in Texas it is supposed 

 that the foreign swarms came from the Eocky Mountain region of Colo- 

 rado. Sometimes, however, the swarms pass southwest over the mount- 

 ains. 



Mr. Holly (see Appendix 7) reports that one year, in the upi)er 

 valley of the Eio Grande, the locusts came from the west across the 

 range in immense numbers. In the Saguache Valley the course of the 



