﻿OF THE STATE ENTOMOLOGIST. 



1859, us is well known, there Avas an interyening J pace between the border settleoients of 

 Nebraska and the eastern base of the mountains of two or three hundred miles in which 

 there were no potato patches. How are we to account for its brldifino: this space ; what 

 induced ittotakeup its line of march across this barren region in which there were no 

 settlements ? Is it not much more reasonable to suppose the plains themselves formed its 

 native habitat, and that as soon as the pioneer settlements reached this region and the 

 potato was introduced, it commenced its attack upon it. and then began its march east- 

 ward along the cultivated area? — Western Rural, Dec. 4. 1875. 



The weak points in the above reasoning are that it implies, first, 

 that the insect travels only from potato patch to potato patch, and 

 that there must have been potatoes at every few miles between the 

 point west of Nebraska where the beetle was first noticed on culti- 

 vated plants and the mountains; second, that no cultivated potatoes 

 were grown on said plains. In truth, however, potatoes were undoubt- 

 edly grown around Fort Keaney and other forts and settlements prior 

 to that time, and the beetle may travel by the spreading of other wild 

 species of Solanuni, and by being carried along water courses or on 

 vehicles. " One point that may be urged in favor of the supposition 

 that the insect was indigenous to the plains that reach far eastward 

 into Kansas and Nebraska, is that it was unobserved in potato fields 

 by certain parties in parts of Colorado after it had reached as far as 

 Iowa. The point is, however, weakened by the fact that it was found 

 in great abundance in Colorado by Drs. Velie and Parry in J864. An- 

 other point that may be made is that it is difficult to imagine that an 

 insect with such a natural predilection for Solanum tuherosum could 

 have passed from settlement to settlement across the plains without 

 its depredations being noticed and recorded. But this last point may 

 also be turned against Prof. Thomas's supposition, since it is also just 

 as difficult to imagine that the potato patches that have been grown in 

 restricted localities on the plains should have remained untouched, if 

 the insect had always existed on those plains. Moreover since potatoes 

 were cultivated on the eastern borders of the plains in Nebraska and 

 Kansas long prior to 1859, there can be no good explanation why the 

 insect did not sooner commence its eastward march, except on the 

 theory of a natural barrier in the shape of the more barren plains, 

 which had up to that time prevented its advance from more western 

 confines. 



Mr. Thomas, in support of his views, supposes that the sand bur 

 '{Solanum rostratum) originally occurred over the plains in question, 

 citing as proof Gray's "Wild on the Plains West of the Mississippi," 

 and the localities given by Porter and Coulter in their "Flora of Colo- 

 rado." Dr. Gray's lani>uage is altogether too general to help much in 

 the argument, and refers to the range of the plant ten years after the 

 beetle had appeared in Nebraska. Porter and Coulter's localities are 

 all in Colorado, and their "Plains of the Platte" doubtless refers to 



