﻿10 EIGHTH ANNUAL REPORT 



the south fork of that river. At all events, nothing: is more certain 

 then that the original home of the plant was the more fertile portions^ 

 of the mountain region, and that, like the beetle which it nourished^ 

 it has been for many years extending its range eastward through 

 man's agency in one way and another, and is now rapidly extending 

 across Missouri, where but a few years back it was entirely unknown. 

 Mr. Carruth, of Topeka, says that prior to 1864, it was unknown in 

 Kansas, and Mr. C. W. Johnson, of Atchison, writes me that the com- 

 ing of Doryphora and of the weed in question were cotemporaneous- 

 in that section ; that the northern dispersion of the plant from the- 

 South-west, through the Texas cattle traffic, afforded the means by 

 which the beetle passed the great stretches of prairie lying east of its 

 native haunts. 



Bearing in mind that as early as 1821 Say reported the beetle suf- 

 ficieudy common on the upper Missouri, and that it flourishes most 

 in the more northern of the States, I think we may justly conclude 

 that the native home of the species is the more fertile country east of 

 the mountains, extending from the Black Hills to Mexico, where it 

 becomes scarce, and is represented by DorypJiora undecemlineatco 

 and D. melanothorax* Putting all the facts together, we may also- 

 conclude that it crossed the great plains through man's agency. That 

 it first reached the more fertile cultivated region to the east, in Ne- 

 braska, finds explanation, perhaps, in the fact that travel was greatest 

 along that parallel, and that the insect's natural range extended fur- 

 ther eastward in those more northern parts, just as the mountain re- 

 gion does in Wyoming and Dakota. 



On the whole, Walsh's theory is doubtless at fault, and needs 

 modification in so far as it implies that the ins'ect necessarily came 

 from Colorado, but. I can but think tliat Doryphora came from the 

 Rocky Mountain region, and that civilization, in the way of traffic,, 

 travel, and settlement on the plains, was the means of bringing it, and 

 that if we put not a too strict construction on his language, Walsh's 

 views are in the main correct. 



THE POISONOUS QUALITIES OF THE INSECT. 



Some interesting experiments, to test the poisonous qualities of 

 these insects, were made during the year by Messrs. A. R. Grote and 



•Mr. W. S. M. cl'Urhan mentions in the February (1870) number of the Entomologist's MoiHhbj 

 Magazine (London) finding a specimen of the beetle in a case of Coleoptera sent from New (Jrenada a.s 

 long ago as ISl.i. I do not believe XQ-Jineatn occurs there, and am strongly of the opinion iliut some one 

 of the similarly marked and closely allied species has been mistaken for it iiy IMr. d'Uiban. The 11- 

 lincata, for instance, which Stal re))()i-ts from Mexico, Costa Hica, Bagota, and Bolivia might easily lie so 

 mistaken, and was for some time actually so mistaken by the members of the Belgian Entomological 

 Society in the discussions had in that body about a year ago as to the possibility of the importation of 

 our Colorado Potato- l)eetle. 



