62 Kansas Academy of Science. 



LOCUST FLIGHTS EAST OF THE MISSISSIPPL* 



BY TROF. C. V. RILEY, OF 1ST. LOUIS'. 



To the unscientiHc mind there are few things more difficult of appreiiension than that 

 species, whetlier of plants or animals, should be limited in geof^raphical range to areas 

 not separated from the rest of the country by any very marked barriers, or by visil)le 

 demarkations. Yet it is a fact well known to every naturalist, and the geographical 

 distribution of species forms at once one of the most interesting and one of the most 

 important studies in natural history. Some species have a very limited, others a very 

 wide, range; and while in the course of time — in the lapse of centuries or ages — the 

 limits have altered in the past and will alter in the future, they are, for all practical 

 purposes, permanent in present time. These limits may in fact, for the purpose of illus- 

 tration, be likened to those which separate difl'erent nations. Though frequently divided 

 by purely imaginary lines, the nations of Europe, with tlieir peculiar customs and lan- 

 guages, are well defined. Along the borders where the nations join, there is sometimes 

 more or less commingling; at other times the line of demarkaiion is abrupt — ^and in no 

 case could emigrants from the one long perpetuate their peculiarities unchanged in the 

 midst of the other. Yet in the battle of nations the lines have changed, and the map of 

 Europe has often been remodeled. So it is with species. On the borders of the areas 

 not abruptly defined, to which species are limited, there is more or less modification from 

 the typical characters and habits; w'aile in the struggle of species for supremacy, the 

 limits may vary in the course of time. The diflercnce is, that the boundaries of nations 

 result from human rather than natural agencies, while those of species result most from 

 the latter, and are therefore more permanent. It is scarcely necessary to add that 

 these remarks apply to species as they are found in nature, and uninfluenced by man. 

 The spread of species by man's direct or indirect influence is equally interesting; but it 

 is not my purpose to consider it in this connection. 



I found some difficulty at the late conference of Governors at Omaha to consider the 

 locust problem, in satisfying those present that the Rocky Mountain locust could not 

 permanently thrive south of the 44th parallel or east of the lOOtli meridian, and that 

 there was no danger of its ever extending so as to do serious damage east of a meridian 

 line drawn a little west of the center of Iowa. They could not see what there was to pre- 

 vent the pest from overrunning the whole country, and thought that Congress should be 

 appealed to not alone on behalf of the country that had suffei-ed from its ravages, but on 

 behalf of the whole country that is threatened therefrom. In my last two reports I have 

 discussed the native home of the species, and I will here endeavor to pi-esent the condi- 

 tions wliich prevent its permanent settlement in the country to which it is not native. 



Briefly, the species is at home and can come to perfection only in the high and dry 

 regions of the Northwest, where the winters are long and cold and the summers short; 

 and whenever it migrates and oversweeps the country to the south or southeast, in which 

 it is not indigenous, the changed conditions are .such that the first generation hatched out 

 in that (to it J unnatural climate, either forsakes it on the wing, or peVishes from debil- 

 ity, disease and general deterioration. On the soundness of this conclusion depends the 

 future welfare of the most of the more fertile States between the Mississippi and the 

 Rocky Mountains ; and science, as well as pa*t experience, shows it to be sound. Upon 



*This article was first prepared for the Scientific American, and was read before the Kansas Academy 

 by request. 



