Origin and Diffusion of Blissus leucopterus and Murgantia histrionua. 



145 



Indian came a decline in prairie fires, and the early settler, beginning 

 where the Indian left off, burned over the uncultivated areas in the 

 fall to protect his buildings, or the dried grass, was fired by sparks 

 from locomotive engines passing over widely separated lines of rail- 

 way. But gradually these tracts of native grass lands would become 

 so interspersed with cultivated fields that prairie fires as we have 

 termed them, no longer occurred. In his second report already 

 referred to, Dr. Fitch states that at Sandwich, Illinois, the insect 

 began its ravages in wheat fields in 1850. This was ten years after 

 the Pottawattama Chief, Shabbona, and his tribe abandoned the coun- 

 try, and two years before my father settled in that immediate locality, 

 and I know from personal experience that there was then only a 

 limited cultivation of grains, and a decline in the burning over of the 

 grass lands in the fall, was followed by rapid increase in the abundance 

 of this species, and in a locality where all available information points 

 to its having been able to sustain itself and increase in numbers while 

 subsisting upon the native grasses. I feel that I am justified in sup- 

 posing that a similar condition would result in a corresponding 

 increase elsewhere.* 



We will now turn to Mr. Marlatt's suggestion that the clustering 

 about the roots of tufts of grass is the normal and ancient habit of 

 hibernation. But 1 shall go farther and add, also, the gregarious 

 habits of the larvae and pupae; Dr. Fitch witnessed this mode of 

 hibernation in Illinois, in 1854, while Dr. Neal observed the same 

 phenomenon in Oklahoma, in 1894, forty years later, so that we have 

 absolute proof that the habit has been followed at several, widely sep- 

 arated, inland points, for nearly half a century ; and Mr. Schwarz has 

 shown that this habit at present prevails along the sea coast, from 

 1,000 to 1,500 miles distant. Along the coast, where grass grows in 

 tufts, it is absolutely necessary for these insects to congregate together 

 in masses, but in the Mississippi basin, or at least over the greater 

 portion of it, the grasses are much more evenly distributed, yet we 

 find the habit as closely adhered to as elsewhere, except it be in 

 patches of closely matted blue grass. Probably no one, however 

 unobserving, has failed to notice the persistency with which the larvae 

 and pupae adhere to their gregarious habits. That the very young 



* Professor Lugger writes me that the insect does not occur in his State on 

 the prairies, but in the timbered portions, except where covered by pines. 



