﻿OF THE STATE ENTOMOLOGIST. 165 



Iheir issue to the east and south, and thus, in the end, prove their 

 destruction. For in the Mississippi Valley they are doomed, sooner 

 or later. 



There is nothing more certain than that the insect is not autoch- 

 thonous in West Missouri, Kansas, Nebraska, Iowa, or even Minnesota, 

 and that when forced to migrate from its native home, from the causes 

 already mentioned, it no longer thrives in this country. 



That the native home of the species is sub-Alpine, is proved by 

 the fact of its abounding to such an extent in British America, and of 

 its breeding in the higher mountain elevations, even up to the peren- 

 nial snows. In fact, so high up does it breed that it often hatches so 

 late in the season as to be overtaken by the cold of the succeeding 

 Winter before acquiring growth, when of course it perishes without 

 begetting. The truly Alpine country cannot, therefore, be its native 

 home ; and those found breeding at such a height must be the prog- 

 eny of others which flew from the plains, either east or west of the 

 auountains. Physical barriers on the high mountain summits put a 

 limit to the insect's extension and propagation, just as they do in the 

 Mississippi Valley. 



Such are my opinions, based upon my own observations in Mis- 

 souri, Kansas, Nebraska and Colorado ; on those of a large number 

 of correspondents, and especially upon the experience of men like 

 Mr. By ers and Prof. Thomas, who have given the subject particular 

 attention. In treating of the native home of the species, I have con- 

 fined myself, as in all other cases in speaking of the insect, as much 

 as possible, to the country east of the Rocky Mountain Range: I 

 deave to others to trace its history beyond the mountains. 



Beyond the boundary line indicated in my map (Fig. 32), they did 

 not reach in 1874, and beyond that line I do not believe they will ever 

 ■do any damage. Not that they may not extend to some extent be- 

 yond that line, in years to come, or that the young, hatching in 1875, 

 will not push beyond it; for I have numerous records to show that 

 they have occurred as far as the western point of Lake Superior, and 

 that they have even reached the Mississippi in parts of Iowa: but in 

 all such instances they appeared in scattering numbers only, and did 

 ■no material damage. They were the last remnants of the mighty 

 armies from the mountains, moving and blowing about, diseased, para- 

 sitised, intestate and wasting away. 



Well is it for the people of Missouri ; well is it for the people of 

 the Mississippi Valley, generally, that this insect cannot go on multi- 

 inlying indefinitely in their fertile fields 1 Else, did it go on multiply- 



