134 THE CANADIAN ENTOMOLOGIST. 



residence here, where I have had ample opportunity for observation. My 

 most important discovery is that this species is double brooded. This is 

 evident from the fact that in 1873 large numbers came here from the 

 south, laid eggs and produced a second brood that flew south in August 

 of the same year. This accounts for their migrations. They can not be 

 local anywhere, because there would not be sufficient herbage to support 

 a second brood in a region already laid bare by the first ; and because in 

 the northern part of their range the season is not long enough to mature 

 two broods. They must, therefore, migrate every year ; and their 

 migrations are conducted as follows : 



Hatching in Texas, New Mexico and Arizona early in spring, these 

 insects, as soon as matured, fly north and deposit their eggs on this 

 latitude about the last of May, although they arrived here this year as 

 early as May 12th. They probably do not lay many eggs south of 

 Nebraska, but they go much farther north. The second brood being 

 able to fly in August, goes south with the first favorable wind, reaching 

 Texas in September, where they deposit eggs to lie over winter. But as 

 eggs were deposited by the first brood all along their route, from Kansas 

 probably to the northernmost limit of vegetation ; the young from these 

 eggs are proportionally later, and, as they acquire their wings and fly 

 south during the autumn months, each successive brood necessarily falls 

 shori of the extreme southern limit reached by its immediate predecessor, 

 and many being retarded by contrary winds, cold and storms, eggs are 

 deposited over nearly the whole extent of country traversed by their 

 ancestors in the spring. 



The next spring, the new brood hatching in Texas and all hatching 

 farther north that acquire wings earlier than the 20th of June or 1st of 

 July, fly north, while those maturing later fly south. They deposit eggs 

 that produce a second brood, as before, which lays eggs for the spring 

 brood. The second brood always flies south. Thus we see that this 

 grasshopper is not forced upon its migrations for want of food, as is com- 

 monly asserted by Entomologists, but is guided in its flights by that 

 instinct which teaches every insect to provide for its young. The natural 

 habitat of this insect is probably the plains lying east of the Rocky 

 Mountains, where it goes through its annual migrations as I have 

 described. Now, let us see how it can spread into the cultivated districts 

 of the Mississippi valley without moving directly east. When ready to 

 fly, it always waits for a favorable wind ; and, if it is going north, will take 



