Williams' " The Aphididae of Nebraska " 1 1 



SYNOPTIC TABLE OF SPECIES FEEDING ON ARTEMISIA, IN AMERICA 



A. Cornicles very small, not longer than wide. 



Microsiphum canadensis Williams 

 AA. Cornicles longer and more conspicuous. 



B. Conspicuous capitate hairs or spines covering the body. 



Macrosiphum artemisicola Williams 

 BB. Body not bearing capitate spines. 



C. Sensoria on antennal segments III and IV, of winged female. 



D. Body dark green and with a metallic luster. 



Mac. frigidae Oestlund 



DD. Body reddish wine color Aphis artemisicola Williams 



DDD. Body green A. canae Williams 



CC. Sensoria not present on antennal segment IV, of winged 

 female. 



E. Segment III and VI filament subequal in length. 



Mac. ludovicianae Oestlund 

 EE. Segment VI filament longer than III. 



F. Antennae shorter than body; body pulverulent. 



Aphis frigidae Oestlund 

 FF. Antennae longer than body; body not pulverulent, 



Mac. cowenii Hunter 



44. A. atriplicis Linnaeus. 



45. A. canae Williams. 



" Aphis canae n. sp. Type No. 54. On Artemisia cana, Squaw 

 Cr., 6/24, '90." 



On this sHde are six immature and one winged viviparous 

 female, the latter having the wings torn off and the tips of its 

 antennae broken off. It is stated in the description of this species 

 that segments VI base and VI filament are subequal. Only one 

 of the antennae is not broken off below the sixth segment and in 

 this case the basal portion and filament are subequal but the end 

 of the filament is plainly broken off so that it is impossible to 

 say how long the perfect segment may have been. Possibly this 

 broken segment led Williams to consider the base and filament 

 subequal in length. Of the six immature individuals on the slide, 

 four have the base and filament of segment VI subequal and two 

 have the filament much longer than the base. Further, the 

 winged is characterized as follows: Antennae on conspicuous 

 frontal tubercles; segment III bears 19 to 22 irregularly placed 

 circular sensoria, and IV, 7 to 9. The tip of the beak is excep- 



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