1877. ] The Rocky Mountain Locust. 665 
lieved —as they popularly are—to express absolute creations 
that have existed for all time. 
As with other species, so it is with the locust under considera- 
tion. The species is a denizen of the plains regions of the 
Rocky Mountains to the west and northwest of tis. It breeds 
continuously and comes to perfection only in those high and dry 
plains and prairies; and though at intervals it overruns much of 
the lower, moister country to the east and southeast, yet it never 
extends in a general way to the Mississippi. But there are spe- 
cies east of the Mississippi that are so closely allied to it that the 
ordinary farmer cannot, without a little special knowledge, ap- 
preciate the difference, and entomologists, even, are not of a 
mind as to whether they should be called species, varieties, or 
races, etc. The two species most closely allied to the Rocky 
Mountain locust are the red-legged locust ( Caloptenus femur- 
rubrum) and the Atlantic locust (Caloptenus Atlantis). Both 
are wide-spread species, but are either rare or do not occur in the 
home of spretus. The differences between the three species I have 
elsewhere given in detail; for the present purpose it suffices to 
say that the distinguishing characters, most easily observed by 
the non-entomologist, are the relative length of the wing and the 
structure of the terminal joint of the male abdomen. The Rocky 
Mountain species has the wings extending, when closed, about 
one third their length beyond the tip of the abdomen, and the 
last or upturned joint of the abdomen narrowing like the prow 
of a canoe, and notched or produced into two tubercles at top. 
The wings of the red-legged locust extend, on an average, about 
one sixth their length beyond the tip of the abdomen, and the 
last abdominal joint is shorter, broader, more squarely cut off at 
top, without terminal tubercles, and looks more like the stern 
of a barge. 
The Atlantic locust, though smaller than either, is in other-re- 
spects intermediate between the two, but in relative length of 
wing and structure of the anal joint in the male, most related to 
spretus. ' 
We should encourage the locust’s natural enemies. Practically 
this is not possible with many of the smaller parasitic and preda- 
ceous kinds; they are beyond our control. With many of the 
larger locust enemies, however, as in the case of birds, it is feasi- 
ble. One of the most effectual ways of accomplishing it is to of- 
fer a reward for hawk-heads, as Colorado has done. The intro- 
duction of such hardy locust-feeding birds as the grackle and the 
