﻿40 NINTH ANNUAL REPORT 



existed : its management is considered part of potato-culture, and its 

 natural enemies assist man to that degree that its effect on the crop 

 is less felt. The quality of the tuber was very seriously affected 

 through the defoliation which the vines so generally endured, and it 

 was at one time difficult to get a non-watery potato on our western 

 boards. 



THE MODIBMCATIOX IT HAS UNDERGONE. 



In previous Reports I have, from year to year, shown how the 

 species, as it spread over the country, became modified in habit, and 

 increased the number of its food-plants. It has also undergone con- 

 siderable modification in character. Specimens which I have exam- 

 ined from different parts of the country, show great variation in 

 the marks of the thorax, in size, in coloration, and even in the orna- 

 mentation of the elytra and legs. The yellow varies from deep gam- 

 boge to almost pure white, the black line along the elytral suture is 

 either very distinct or as obsolete SiHUijuncta; while some specimens 

 have the pale legs and the femoral spot, more or less distinct, which 

 are so characteristic of this last. In northern Iowa and Wisconsin I 

 have seen millions traveling over the ground, the average size of the 

 individuals being not more than half that of the more typical speci- 

 mens ; and the general ground-color being white rather than yellow. 

 In its southern range the colors tend to brighten and the black to 

 become more metallic. Indeed, the variation which it has already 

 exhibited furnishes interesting material for the close species makers. 



AN ADDITION TO ITS NATURAL ENEMIES. 



Among the many different enemies of this potato depredator that 

 I have treated of, only one true parasite {Lydella doryphorm) was, 

 up to 1876, described, and that an internal one. In the summer of 

 1873, Mr. H. C. Beardslee, of Paynesville, Ohio, sent me a mite with 

 which he found Doryphora attacked, and last summer this same mite 

 was found by Mr. W. R. Gerard, to very generally infest the beetles 

 around Poughkeepsie, N. Y. It sometimes so thickly crowds and 

 covers its victim that no part of this last is exposed, and the beetle 

 thus infested languishes and eventually perishes. This minute para- 

 site is about the size of the head of a small pin, broadly oval, de- 

 pressed, the body in one piece, somewhat tough above, and yellowish- 

 brown in color. It is not uncommon on other beetles, and is closely 

 allied to a well known European mite parasite of beetles and other 

 Articulates— the Vropoda vegetans. This last is described by authors 

 as possessing the peculiarity of attaching itself to the hard, shelly 

 parts of its victims by means of a threadlike filament that issues 

 from the posterior part of the body. A careful study of our American 



