146 APHIDS OF THE ROCKY MOUNTAIN REGION 
rostral IV+V is a more constant character in aphids than that of other ap- 
pendages and seems to definitely separate these two forms. 
The infestation of these two host plants is unusual and perhaps doubtful. 
As the specimens from Artemisia were alatae they might have been only 
temporary visitors on this plant: Chrysothamnus was evidently a true host 
since here the aphids were colonized. 
Aphis kachena Hottes 
Aphis kachena Hottes, 1934:2; Palmer, 1936b:737. 
Apterous Summer Vivipara. Dark green, mottled with brownish black in areas and 
patches; antenna yellowish to dusky; cauda and anal plate brown to blackish; cornicle pale; 
tibiae pale with black tips. Body length 1.30-1.60; antenna .75-.90 (in some III and IV co- 
alesced); hind tibia .60-.90; hind tarsal II .10-.11; rostrum surpassing 2d coxa. Dorsal in- 
tegument heavily denticulate as is the cornicle. Lateral tubercles very small and [ poinies 
= 0. 09) we Re ant 
120g 1s) nents ar pag 
EN ABTob. a A 
Fig. 161. Aphis eae i 
Alate Vivipara. Head and thorax dark brown; abdomen yellow-green with dusky dorsal 
bands or patch and lateral areas; cornicle pale to dusky; cauda and antenna dark; tibia yel- 
low-brown. Body length 1.50-1.60; hind tibia .90-1; hind tarsal II .10-.12; antenna 1.10-1.30; 
cornicle cylindrical, with flange, covered with fine sharp points or denticles. Cauda bluntly 
tapering and bearing 3 pairs of hairs. 
Collections. In flower heads of Castilleia rhexifolia and sp. Colorado: 
Skyway, Grand Junction and Pingree Park. Utah: Hoop Lake, Bryce Canyon, 
Toquerville and Hurricane. Alate and apterous viviparae July 1 to Sept. 1, 
alate fall migrants until Oct. 15; rare. 
Holotype. U.S.N.M. Paratypes, Colo. Agr. Exp. Sta. Collection. 
Chief Distinguishing Characters. Dark color of aptera with no dusky specks 
discernible at hair bases, numerous sensoria (not fewer than 36) on III of alate 
vivipara and very pronounced finely denticulate surface of the cornicle, es- 
pecially in the aptera. 
Aphis knowltoni Hottes and Frison 
Chaitophoroides middletonii (Thomas) (misidentification), Knowlton, 1929c:34. 
Aphis knowltoni Hottes and Frison, 1931a:199, 
Apterous Fall Vivipara. ‘‘Greenish blue to yellowish green; reticulated with grayish 
pruinose; lateral and dorsal black areas covering part of each body segment; cornicle, cauda 
and anal plate black.” Body length 1.8-2.3; across eyes .40-.43; hind tibia .75-.90; antenna 
1-1.20; rostrum attaining to 3d coxa. Hairs erect and fine; on antennal III .03-.05, on cauda 
at least 8-9 pairs. 
Dorsal 
Body 
A5-.20 a 
Marking 
Co 
Fig. 162. Aphis knowltoni 
