H. F. WILSON 95 



0.27 mm. Length of nectaries, 0.22 mm.; length of cauda, 0.066 mm.; length 

 of wing, 2.22 mm.; width, 0.67 mm. 



Aphis frigidae Oestlund ^ (Plate VIII, figs. 20 to 24.) 



Found in company with M. frigidae Oestlund on Artemesia 

 tridentata throughout the eastern part of Oregon. 



General color dark brown with a greenish tinge which is not at first evident 

 on account of a general light colored appearance produced by a coating of fine 

 white powder. In the original description of this species Oestlund speaks of 

 "a rather thick pubescence of fine and short hairs" which I have been unable 

 to discover. The entire body is, however, covered with long curved hairs 

 having flared tips. Antennae black except at the base of the third and the 

 first and second segments. Legs, nectaries and cauda dusky to black. The 

 antennae are as long as the body and are not mounted on antennal tubercles. 

 Head nearly straight in front, eyes black and with ocellus weak or entirely 

 wanting. Abdomen oval and round and curved with numerous light spots 

 which are the tubercles from which the hairs originate. The nectaries form 

 one of the most important specific characters of this species. They are cylin- 

 drical throughout and the tip is widened out to twice the width of the main 

 part. Cauda short and rounded at the tip. 



Measurements: Length of body, 1.6 mm.; width, 0.78 mm.; length of anten- 

 nal segments: III, 0.25 mm.; IV, 0.23 mm.; V, 0.22 mm.; VI, 0.11 mm.; spur, 

 0.42 mm. Length of nectaries, 0.42 mm.; length of cauda, 0.12 mm. 



Aphis artemesicola Williams* (Plate VIII, figs. 16 to 19.) 



What is beheved to be this species was taken on Artemesia 

 tridentata in company with M. canadensis Williams at Salisbury, 

 Oregon, July 26, 1914, Only the apterous forms were taken 

 but the specimens agree fairly well with Williams' description. 

 The number of sensoria on the third antennal segment do not, 

 however, correspond with those shown by Davis in his critical 

 review of Williams' species.^ 



General color shining wine red; antennae about two-thu'ds the length of the 

 body. Antennal segments one, two and the greater part of three dusky yeUow; 

 remaining parts deep black. Legs black except at base of femora and the basal 

 half of the tibiae. Nectaries black; cauda black at tip, dusky red toward base. 

 Antennae with from 2 to 8 sensoria on the third segments, mostly 2 to 4. Nec- 

 taries slightly tapering and each one with about four haii's; tip flanged. Cauda 

 short and broad at the base, and pointed at the end. Body with pointed 

 hairs. 



^ Fourteenth Annual Kept. Geol. and Nat. Hist. Surv. Minn., 1886, p. 46. 

 ^ "The Aphididae of Nebraska," University of Nebraska Studies, X, no. 2, 

 p. 37. 

 ' Loc. cit. 



TR.\NS. AM. ENT. SOC, XLI. 



