﻿OP THE STATE ENTOMOLOGIST. 155 



are ordinarily heavy-bodied and short winged, the power of extended 

 flight, and there is little doubt, in my mind, that the same exception- 

 ally hot, dry seasons which permit this undue multiplication, alsa 

 modify the individuals, and cause a decrease in bulk and increase in 

 wing-power. The facts support this view, for the flying specimens of 

 diiferentialis sent to Prof. Thomas had, as he writes me, " the body 

 lighter and the wings longer, and some of that peculiar fierce appear- 

 ance belonging to migrating specimens ;"' and I have specimens from 

 Kansas and Minnesota which difi'er so much in these respects from the 

 more normal specimens as found with us in ordinary seasons, that they 

 can scarcely be recognized as the same species. The casual observer 

 knows how thoroughly plants are modified in size and habit by season 

 and condition : the same holds true of insects, and more particularly 

 in certain groups. 



Given that over the vast prairie region of Central Illinois, the in- 

 sects were as thick as I found them in many of our own fields^ 

 where every step would cause two or three hundred to rise, and let 

 this migratory instinct be developed, and the mystery of the Illinois 

 flights vanishes. They are exceptional local phenomena: they are 

 neither as strong nor as long sustained as those of the Rocky Moun- 

 tain species; nor are they in any sense to be as much dreaded. 



In short, whenever the climate and conditions in the Mississippi 

 Valley approach those existing in the native home of the Rocky 

 Mountain Locust, some of our native species, and especially those 

 nearest akin to it, also approach it in habit. If the climate of Illi- 

 nois and Missouri were to permanently change in that direction, these 

 species would become permanently modified ; but as there is no im- 

 mediate danger of such a contingency, the Rocky Mountain Locust is 

 the only species, here considered, that can properly lay claim to the 

 migratory habit. 



PROSPECTS IN 1876. 



The people in our western counties are very naturally quite inter- 

 ested in the locust prospects during the coming year; the more so 

 that the story has been widely circulated that the danger was greater 

 than ever before. As an example I take the following from an edito- 

 rial in the St. Louis Glohe- Democrat of the 26th of December last : 



Persons whose experience in such matters entitles their opinions to respectful 

 consideration, declare that the Summer sun of 1876 will hatch such swarms of grass- 

 hoppers in the West as have never before been seen, and that the tract of country in 

 which they will prevail will be wider than ever before, reaching from a long distance 

 west of the Black Hills to the center of Missouri and Iowa. 



I know of no persons whose experience deserves respectful con- 

 sideration who have declared anything of the sort ; and so opposed to» 



