H. F. WILSON 89 



IX. Body covered with specialized setae. (Fan-like at tip.) 



Macrosiphum artemesicola Williams 

 Body covered with capitate setae. 



Macrosiphum frigidae Oestlund 

 Body covered with pointed setae. 



Macrosiphum ludovicianae Oestlund 



Chaitophorus tridentatae new species (Plate VI, figs. 22 to 25.) 



Found throughout eastern Oregon on Artemesia tridentata. 

 This species is not always easy to locate on account of the simi- 

 lai'ity in color of the l)ody to that of the plant. The entire body 

 is covered with specialized setae which are fan shaped at the tip. 

 These give the appearance of fine white hairs or powder. Most 

 of the individuals are found in rows, one behind the other on the 

 leaves. A good many are found in around the base of the leaf 

 and flower stems. 



Apterozis viviparous female: General color, light green with more or less of 

 a powdery appearance. Abdomen with a darker green line along the center. 

 Antennae dusky at the tip and shading to light green at the base. Legs with 

 tarsi black; remaining parts and the cauda dusky. Body covered with spe- 

 cialized setae which are broadly fan shaped at the apex. Nectaries not much 

 more than pores and hardly distinguishable among the speciaUzed setae. 

 Antennae shorter than the body and without distinct tubercles. First anten- 

 nal segment strongly gibbous and with two or three specialized setae, one of 

 which is found at the apex of the segment. Second segment with one, third 

 with four, fourth with two and fifth and sixth without setae. Legs have no 

 specialized setae. Cauda slightly ensrform and not visible from above. 

 Nectaries so short that shape and size cannot be definitely settled with material 

 at hand. 



Measurements: Length of body L38 mm.; width 0.67 mm. Length of 

 antennal segments: III, 0.154 mm.; IV, 0.11 mm.; V. 0.135 mm.; VI, 0.11 mm.; 

 spur, 0.154 mm.; length of cauda, 0.11 mm. 



Alate viviparous female: Light green in color as in apterous form. Head and 

 thorax light brown. Antennae Ijlack at the tip and shading to light green at 

 the ba.se. Legs light green with tips of the tibiae and the tarsi black. Cauda 

 light green, nectaries invisible. Entire body covered with specialized setae 

 as in the apterous form. Third antennal segment with 4 or 5 large sensoria, 

 wings long and slender, venation normal. Cauda rounded and tapering at 

 the tip. 



Measurements: Length of body, 0.88 mm.; width, 0.30 mm. Length of 

 antennal segments: III, 0.22 mm.; IV, 0.135 mm.; V, 0.176 mm.; VI, 0.135 

 mm.; spur, 22 mm. Length of cauda, 0.09 mm.; length of wing, 1.84 mm.; 

 width, 0.71 mm. 



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



