﻿OF THE STATE ENTOMOLOGIST. 109" 



NATIVE HOME OF THE SPECIES. 



The question as to the native home of the species will always in- 

 terest. Having carefully weighed all that has been written on the 

 subject during the year, and eagerly sought all information that 

 might shed light upon it, I am firmly convinced of the general truth 

 of the views enunciated under this head in my last Report. The 

 species is, in fact, '' at home in the higher altitudes of Utah, Idaho, 

 Colorado, Wyoming, Montana, northwest Dakota and British Amer- 

 ica. It breeds in all this region, but particularly on the vast hot and 

 dry plains and plateaus of the last named Territories, and on the 

 plains west of the Mountains." In that country alone does it come to 

 perfection for a series of years, and in that country alone can it 

 become so prodigiously multiplied, and be borne by the wind to such 

 distances as to overrun the country already indicated (p. 106) where it 

 is not indigenous, and reach as far east as it did in 1874. To this end, 

 also, a combination of favorable conditions that only occasionally oc- 

 cur, are necessary. The best evidence of the soundness of a theory is its 

 power of absorbing newly ascertained facts and of overcoming objec- 

 tions that are raised against it. The facts already adduced as to the 

 direction and destination of the departing swarms from the lower 

 Missouri and Arkansas river country add strength to the theory. I 

 will here briefly notice the principal objections to it, made by Mr. S. 

 H. Scudder, as a means of adding to the arguments already brought 

 forward. In the Proceedings of the Cambridge Entomological Club 

 for June 11, 1875, as reported in Psyche (the organ of the club), for 

 Febr. 1876 (Vol. 1, p. 144) occurs the following : 



Mr. Scudder offered some remarks on Mr. Riley's account of Caloptenus spretus in 

 his recent Annual Report. The speaker doubted whether these insects took flight 

 from the heart of the Ilocky Mountains [1] to the localities in which they were destruc- 

 tive, passing over the wide expanse of arid plains which intervene, because there has 

 been no record of their occurrence in swarms in these plains, and there is sufficient 

 ground for the supposition that they may have developed in the immediate vicinity of 

 the regions which they devastate [2]. It is well knov/n that among other insects there 

 are years in which individuals are suddenly very abundant, and intervening series of 

 years in which few are to be found. It is also known that a few of these locusts can be 

 found in Kansas and Missouri, and in I'act from Texas to Manitoba eyery year, [3] so it 

 seems hardly necessary to look so far for the derivation of the destructive swarms. 

 Moreover, the circumstance, mentioned by Mr. Riley, that the locusts get tired after 

 repeated tlights, is an additional argument against the supposition that they came from 

 a great distance, for the rate at which their strength diminished seemed out of all pro- 

 portion to the activity of the insects at the time of their first ravages. [-1.] 



[1] I have nowhere spoken of the " heart of the Rocky Moun- 

 tains " as the source of the swarms that take their flight to our coun- 

 try. On the contrary, my language is very different {vide Rep. 7, p. 

 163), and it is upon this kind of misapprehension that Mr. Scudder's 

 remarks are based. 



