﻿124 SEVENTH ANNUAL REPORT 



noticed at their worii along roads and roadsides than in fields, a fact 

 which has also had something to do in forming the popular impression. 

 Newly broken or plowed land is not liked; it presents too loose a sur- 

 face. Moist or wet ground is always avoided for the purpose under 

 consideration. During the operation the female is very intent on her 

 work and may be gently approached without becoming alarmed, 

 though when suddenly disturbed she makes great efforts to get away 

 and extricates her abdomen in the course of half a minute or more. 



THE MIGRATOEY INSTINCT AND GREAT DESTRUCTIVE POAVER BELONG TO BUT ONE 

 SPECIES WEST OF THE MISSISSIPPI. 



Being anxious to ascertain whether the injuries reported in the 

 different parts of the country between the Mississippi and the Rocky 

 Mountains were all caused by one species, or whether others joined 

 their forces in devastating the country, I took some pains to procure 

 specimens from as many different localities as possible. What with 

 specimens collected in previous years in Colorado, and received from 

 Missouri and Texas, and those obtained in 1874, I now have material 

 from Manitoba, Minnesota, Nebraska, Iowa, Colorado, Kansas, Mis- 

 souri, Indian Territory and Texas. In each instarce it is the same 

 species that proves such a scourge. As we shall presently see, the 

 same species occurs in Wyoming, Utah, Idaho, Nevada, Montana and 

 Arizona. I know nothing of the migratory species which at times 

 does damage in California and other parts of the country west of the 

 Rocky Mountains ; some have supposed it to be (Edvpoda atrox Scud- 

 der ; but I agree with Mr. Thomas that, with its comparatively short 

 wings, this species cannot sustain lengthened flight, and the probab- 

 ility is that the spretus under consideration, or a race of it, is the 

 culprit. 



Only occasionally do specimens of some of the more common 

 species accompany the migratory one. Thus the larger and common 

 species, the Two-striped Locust {Caloptenus hivitiatus^ Say) and the 

 Differential Locust {C. differ entialis^ Walk.) which are incapable of 

 migrating to any great distance, and which are common in the Missis- 

 sippi Valley, have occasionally been caught with the apretus^ and 

 sent to me with it. Already existing in the country invaded by the 

 Rocky Mountain species, they were simply gathered up with it. 



Yet, while no other species possesses such wonderful migratory 

 habits, several become so enormously multiplied during certain years 

 in their native homes as to commit very serious injury to vegetation. 

 Of these, I shall speak more fully further on. 



