56 APPLE LEAVKS— -il^AFrLOUSE BESCEIBED, 



Variety 6, nigricollia. The neck not green, but of the same Mack color as tlie 

 head and thorax. Common among aged individuals. 

 e, thoracica. The thorax dull green, with a black band forward of its 

 middle: Toung. 



d, fulviventru. The abdomen pale dull yellow instead of green. 



e, nigriventris. The ?bdomen greenish black, with the row of black dota. 

 along each side, indistinct. 



/, immaculata. The abdomen without any dots or darker colored marks, 

 g, obsoleta. The lateral row of black dots faint a^d scarcely perceptible. 

 h, triseriata. A row of black dots along the middle of the back, as well 



as upon each side of the abdomen. 

 i, bivmcta. Two black bands towards the apex of the abdomen, on it» 



upper side. 

 j, tergata. Abdomen above, with two black bands towards its tip, and 



three rows of black dots anteriorly. 



Several specimens of Plant-lice which I gathered from the 

 leaves of Apple trees, in Mercer county, Illinois, upon the 4 th 

 day of October last, and which at the time of capturing them I 

 supposed were variefies merely of the common species which we 

 have been considering, prove on examination to pertain to a dif- 

 ferent species. They are a size larger and of a shining black 

 color throughout. In the common species the legs are uniformly 

 pale with black feet and knees, the preserved specimen showing 

 this character almost as distinctly as living individuals ; iu these 

 specimens on the contrary the legs are entirely black, or at most 

 brownish yellow at their bases in some instances. The wing- 

 veins moreover diflfier notably from those of Jiphis Mali in several 

 points. They are more slender, and the .fourth vein is relatively 

 shorter and more strongly curved through its whole length. In 

 consequence of this curvature it is nearer to the second fork at 

 Its base than at its tip. Two-thirds of the specimens which were 

 captured at that locality coincide with each other in these differ- 

 ences. This fact would indicate this to be a more common species 

 upon the Apple trees in Illinois than 'the Aphis Mali; but its 

 darker color and larger size rendering it more conspicuous than 

 that species may have occasioned a disproportionately large num- 

 ber of this species to be gathered. It may appropriately be named 

 the Apple-leaf louse {Aphis Malifolia). The specimens show the 

 fiiUowing marks in addition to what has already been stated : 



The Apple-ieap iouse measures 0.15 to the tips of its wings. The third vein of 

 t efore wings is but slightly abortive at its base. The second and third veins are 



