58 INSECTS INJURIOUS TO STAPLE CROPS. 



found to be the best and only means of preventing the loss 

 of then' crops. 



Locusts {Acrididce). 



Plagues of destructive locusts — or what the American 

 farmer terms grasshoppers — have been recorded since the 

 dawn of history. In America the worst devastation has 

 been done by flights of the Rocky Mountain or Migratory 

 Locust [Melanoplus spretys Thos.), which swooped down 

 upon the States of the western part of the Mississippi 

 Valley in the years 1873-7G like a veritable horde of 

 mountain robbers. Since then they have several times 

 done considerable injury in restricted localities, but never 

 in such numbers or so generally as to cause apprehension 

 of another " grasshopper plague."' 



Concerning their recent distribution, numbers, and 

 destructiveness, Mr. W. D. Hunter reported after the 

 season of 1897 : '^ There was, this season, a general activity 

 of this species throughout the permanent breeding region 

 greater than at any time in many years. This was brouglit 

 about by a series of dry years, which have resulted in the 

 abandonment of farms in many places. It is, of course, 

 well understood that the absence of serious damage since 

 1876 has been partially due to the settling w^ of valleys 

 in the permanent region. I wisli to make it clear, how- 

 ever, that the dryness is the primary and the abandoning 

 a secondary cause. "' 



The Rocky Mountain Locust. 



Let us first consider this the most injurious species, as 

 the other locusts differ from it in but few essential points 

 other than in being non-migratory. 



