LOCUST OBSERVATIONS IN THE NORTHWEST. 59 
they keep their wings clattering and rattling to such an extent that one 
would suppose they were rattling into pieces. We did some collecting 
at Custer’s battle-field, where we took a large variety of species, as well 
as in most cases a large series of Specimens. Here we also observed 
to a great extent the partiality which certain species exhibited in 
the selection of special food-plants. Again, at Junction City, Mont., 
we made some collections, adding a few to the list of species taken. 
Here, for the first time, we took several specimens of a species of 
@dipodine belonging in the genus Mestobregma, and which almost 
exactly imitates in color a species of Psoloessa which we took on the Lars 
amie River, south of Laramie City. While these two insects so closely 
resemble each other in color they are quite distinct, and as Scudder has 
subdivided the genus Gdipoda they fall into distinct genera. The two 
species in question, however, are both partial to the same food-plant, 
viz., the white or sweet sage, and thus far [ have found neither away 
from where this plant abounds. 
We again collected at a point onthe Yellowstone River about mid- 
way from Trail Creek to the National Park, at the Mammoth Hot 
Springs, and at Henry’s Lake. It was at the former of these localities 
that we found the Mestobregma most abundant. 
While passing along the road near Gardiner, a new town, which is 
to be the terminus of the Park branch of the Northern Pacifie Railway, 
we captured a few specimens of the same species of light-blue-winged 
Trimerotropis that I took last year at Fort Benton, thereby extending its 
range at least to the southern border of Montana. It appeared to be 
quite rare even in its special haunts, viz., a light, almost bare, whitish, 
alkaline soil destitute of rocks. It was also taken in the Lemhi Valley 
of Idaho. At this same locality several other species of closely allied 
locusts were taken. After crossing the main Rocky range to the west 
side a change in the comparative abundance of some species and in 
the total absence or replacement of other species was observed. 
While on the eastern slope we found Circotettix carlingianus quite 
abundant and C. undulatus rather rare, on the western side of the divide 
we found just the reverse. 
The large, red-winged Hippiscus which on the east side is everywhere 
so abundant, and in fact all the red-winged forms, have thus far been 
exceedingly rare, only four specimens having been seen during the five 
days that have passed since crossing the summit. A species which, on 
the eastern side, was met with but occasionally has become quite plenti- 
ful. It is perhaps what Mr. Scudder has called Psinidia wallula. 
Thus far we have found locusts to be most numerous in species at an 
elevation varying from 2,500 to 6,000 feet above sea-level, and on the 
bench-lands in preference to either bottom or mountain lands. While 
most of the Caloptenus and Pezotettix were partial to moist localities 
where vegetation was rankest, the Gidipodine and Stenobothrini, &c., 
