45 
except that Acridium frontalis Thos. was found injuring alfalfa and 
sorghum especially. The natural food of this species is the Helianthi«, 
but in recent years the tendency to become adapted to cultivated plants, 
which has also been observed in the case of Dissosteria longipennis and 
other species, has been quite noticeable. It is worthy of note also that 
sorghum is taken in preference to most other plants, although I saw 
fields of alfalfa and millet rendered valueless by this species. 
Melanoplus bivittatus was scarcely less numerous than differentialis in 
some places, but this does not contradict the above statement that three- 
fourths of the damage was done by the latter species. D. longipennis 
was occasionally met with. Hippiscus corallipes Hald. was not found. 
The Arkansas Valley has been exempt from much injury for several 
seasons, but it is favorable weather conditions and the absence of par- 
asites that have brought about the present state of affairs. The pests 
are increasing, and although they will not be much in evidence next 
year on account of the very natural increase of parasites, the trouble 
will not at least be augmented. Unfavorable weather conditions, such 
as freezing or a late or wet spring, may, however, noticeably diminish the 
number of locusts here. The preponderance of evidence points to the 
fact that the trouble is a permanent one, in spite of the aid given by 
parasites and meteorological conditions, or, at any rate, of frequent 
periodical ovcurrence, and that the work of the farmers and not the 
intervention of Providence is the only way out of the difticulty. 
Destruction is made easy by the fact that the locusts are collected in 
small areas, as has been indicated in the discussion of the situation in 
Nebraska. The parasites nay be abundant one season in one of these 
areas, or may even practically exterminate the locusts infesting it, but 
do not easily spread to the neighboring fields, which may be 3 or 4 
miles distant. Thereupon the locusts begin to increase again in this 
area, aud this process is repeated continuously. The ready means of 
control of the pests by the farmers and the reasons why it is possible 
will be brought out more fully in the discussion of the conditions in 
Colorado, which are much the same. 
COLORADO. 
Rocky Mountain locusts (Melanoplus spretus) were practically absent 
from Colorado this season, although I collected a few specimens in the 
vicinity of Julesburg and at a point directly south of Sidney, across the 
Nebraska line in Logan County. Specimens were by no means numer- 
ous, and I have no doubt that they represent the extreme advance guard 
of the species. Professor Gillette informs me that he knows of no case 
of the occurrence of this species in Colorado in the past six years, add- 
ing, however, that most of his locust collecting has been done along the 
foothills. Certainly it has not been present during this season in more 
than a few counties in the extreme northeastern parts of the State. 
The damage done by the native species reached its greatest extent 
