150 TRANSACTIONS OF THE 



''Rocky Mountain Locust" (ccdoptenus sjrrenus) through the able and 

 exhaustive labors of the United States Entomological Commission^, 

 established by Act of Congress in 1867, especially to grapple with the 

 locust problem. The damages done in the West by locusts during 

 the four years just previous had been enormous. The enemy was 

 still in their midst; his habits and instincts were little known; false 

 and wild theories were advanced by superficial observers; panics 

 were frequent; iinmigration was retarded, and the most dreadful 

 anarchy was imminent. The Commission — composed of Professor 

 C. V. Riley, A. S. Packard, Jr., and Cyrus Thomas — hastened into the 

 field, divided up the labor, and commenced a sj^stematic and most 

 thorough investigation of the scourge — an examination which at 

 once allayed fears and restored confidence throughout the West. As 

 long ago as 1860, Mr. Thomas, then residing in Illinois, collected 

 specimens of this locust, and, as it bore the generic characters of the 

 well-known acridiuvi, but was a new and very voracious species, he 

 named it the acridium spretus. Subsequently it found a place in the 

 family of coloj)tenus, the specific name {sjjretus) being retained. Even 

 the unscientific will allow that these names are very descriptive and 

 appropriate. CalojJtenus means '' beautiful " or " clear wing," alluding 

 to the bright, transparent wings of the genus, and sj^retus is Greek for 

 "hateful," "despised," "dreaded." Certainly well deserved names. 

 The permanent breeding grounds of the Rocky Mountain locust or 

 spretus is a large region on the eastern slopes of the Rockies, from the- 

 Colorado parks northward 200 miles beyond the British boundarj", 

 and embracing a section of the great plains east of the Rockies about 

 1,000 miles long by 350 wide, approximating 300,000 square miles. 



A small, detached locust region lies contiguous to and northward 

 from Salt Lake, and another lies along the Shoshone River, on the^ 

 borders of Idaho and Oregon. A sub-permanent region borders the 

 large permanent region on the east, and extends nearly to the Red 

 River of the North and the borders of Minnesota, divides Nebraska,, 

 and closely approaches Kansas on the south. In this region the 

 locust may remain and breed for several years, but eventually it 

 returns to its home. From these regions irregular forays are made 

 eastward and southward, generally in seasons of drouth. The migra- 

 tory swarms are often hundreds of miles in dimensions, and over two 

 miles high, and so numerous that they obscure the light of the 

 sun. They often continue on the wing several days and nights, and 

 journey over 2,000 miles. But the limits of their marauding excur- 

 sions are clearly and rigidly defined. Seemingly disliking timber, 

 the northern flights cease at the borders of the great forests of British 

 America, met with first along the Saskatchawan. On the east the 

 limitjilmost conforms to the ninety -fourth meridian, crossing Minne- 

 sota, Iowa, Missouri, and Arkansas. On the south the locusts sweep 

 away down to within 50 miles of the Gulf, and along the Rio Grande. 

 The line westward curves upward, so as to nearly exclude New 

 Mexico and Arizona, while on the west it passes through the center 

 of Nevada and the eastern portions of Oregon and Washington. 



DESTRUCTIVE POWER OP LOCUSTS. 



During the years 1873 to 1877 locusts destroyed property and dam- 

 aged the interests of the West to the enormous extent of $200,000,000,, 

 nearly equal to the total destruction of the entire City and County 



