168 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
coal-oil, or any oily or greasy matter, is sure death, provided the oily 
substance comes in contact with the body or any part of it. As quickly 
as the oil touches the insect it spreads rapidly over the skin, covering the 
spiracles or air-holes with a thin film. 
As fields of young grain and corn are sometimes attacked by the 
crickets, one of the best means of getting rid of them adopted in Utah 
is to drive a flock of sheep into the grain-field, keeping them compactly 
herded. By so doing the grain is not materially damaged, we are told, 
and great numbers of the crickets are stamped to death. 
It is obvious that most of the means used in fighting the young of 
the Rocky Mountain locust, and already described at length in the First 
Report of the Commission, may be applied to the cricket. 
Geographical distribution of the species of Anabrus. — The species of this 
genus are characteristic of the central province of the United States, as 
none are found east of longitude 95°, and none on the Pacific slope of the 
Cascade Mountains and the Sierra Nevadas. In fact, the geographical 
limits of the Western cricket are probably nearly or quite co-extensive 
with those of the Rocky Mountain locust. 210 The northern and southern 
limits have not been ascertained. The species are known, however, to 
extend northward as far as Manitoba, and southward into Northern 
New Mexico and into Arizona, but these limits are very indefinitely 
known. 
Within the limits of the central zoo-geographical province there are 
two distinct regions tenanted by different species of Anabrus, the line of 
division being the great continental divide, i. e., the highest range of the 
Rocky Mountains. The great basin, with adjoining regions, extending 
from the Columbia River on the north to Nevada and Central — and 
probably Southern — Utah and Arizona on the south, is tenanted by 
Anabrus simplex; while the eastern flank of the Rocky Mountain range, 
with the great plains eastward to about longitude 97°, extending from 
Manitoba on the north to Northwestern Texas on the south, is the home 
of Anabrus purpurascens and its ally, Anabrus coloradus. 
Mr. Thomas has noticed during his journeys into Utah, Idaho, 
Montana, and Colorado, that whenever he passed to the east side 
of the Rocky Mountain divide, no matter at what point of the range, 
Anabrus purpurascens prevailed, no specimens of Anabrus simplex appear- 
ing; while, on the other hand, when he passed to the next side Anabrus 
simplex prevafled, no specimens of A. purpurascens appearing. He never 
knew of any exception to this ride. Our own observations and the re- 
corded statements of others bear out this conclusion. 211 
So far as ascertained, the northern limits of distribution of Anabrus 
210 While the distribution of the Rocky Mountain locust has been given in the First Report of this 
Commission and mapped, the general characteristics distinguishing the central province from the 
eastern and Pacific or western, have been briefly discussed in the American Naturalist for August, 
1878; the species of Anabrus may be added to the insects there enumerated. 
211 Mr. Thomas has observed A. purpurascens at the following places in addition to Colorado, to wit: 
Nebraska; Southeast Dakota, to the west boundary of Minnesota; on the Sweetwater, in Wyoming; 
also in Montana, from Pleasant Valley, where we cross the range to Virginia City. 
