304 APHIDS OF THE ROCKY MOUNTAIN REGION 
Macrosiphum erigeronensis (Thomas) 
The Canadian Fleabane Aphid 
Siphonophora erigeronensis Thomas, 1877:7. 
Macrosiphum erigeronensis, Hottes and Frison, 1931a:304; Gillette and Palmer, 1934: 
177. 
Apterous Summer Vivipara. Pale to median yellowish green; cornicle black only at tip; 
tibiae pale to dusky; antenna blackish at tips of segments and dusky beyond base of III; 
cauda pale. Body length 2.5; across eyes .47; hind tibia 1.7; hind tarsal II .14-.15; antenna 
2-3; rostrum surpassing 2d coxa. Hairs capitate; on side of abdomen .03-.04. Cauda tapering 
to rather acute point, without distinct constriction, bearing 3-4 pairs of lateral hairs and two 
‘dorsal single ones near tip, with 4-5 hairs near tip capitate, often only straight. 
Alate Vivipara. Same as apterous vivipara except as follows: Head and thorax, cornicle, 
except base, and antenna beyond base of III black; hind tibia 1.35-1.55; rostrum attaining only 
to 2d coxa. Hairs on side of abdomen .03. 
Ovipara. Apterous. Same as apterous vivipara except as follows: Proximal half of hind 
tibia swollen to twice width of narrowest portion, blackish in color and bearing numerous 
sensoria. Body length 2.35; antenna 2-2.2; cauda .25 on median line. 
Male. Alate. Head and thorax dark brown; abdomen brownish green to yellowish brown 
with faint dorsal dashes; all appendages dark. Body length 1.50-2; hind tibia 1; antenna 2; 
cornicle .27-.32; cauda .13-.15 on median line, .18-.20 on side, terminal hair capitate or abruptly 
curved at end; rostral IV+V .12 long. 
op Ta pets: 
A pt. Vin 
” “Alate 
Fig. 361. Macrosiphum erigeronensis 
Collections. On Erigeron canadense and E. subtrinervis. Colorado: Boulder, 
Greeley, Lindland and Fort Collins. Utah: Springdale and Zion Park. New 
Mexico: Pecos. Fundatrices May 16, apterous summer viviparae June 16 to Nov. 
27, alate viviparae June 6 to Nov. 27, sexuales Sept. 28 to Oct. 31; common. 
Type. Not recovered. Neotype, Ill. Nat. Hist. Surv. Collection, No. 5157. 
Chief Distinguishing Characters. Length of unguis (shorter than III), 
length of antennal III (same as cornicle), length of reticulated area on cornicle 
(.20-.24), presence of 1-4 capitate to straight hairs on tip of cauda, pale green 
body, hind tibia, rostrum and cornicle pale with blackish only distally or at 
extreme tip and dorsum of body without dark areas at hair bases. 
Macrosiphum escalantii Knowlton 
Macrosiphum escalantii Knowlton, 1928d:79; Smith and Knowlton, 1937b: 269. 
Tritogenaphis utahensis Pack and Knowlton, 1929: 202. 
Tritogenaphis gutierreziae Pack and Knowlton, 1929:203 n. syn. 
This species seems inseparable from M. erigeronensis. To describe and 
draw it would be but to repeat the description of that species except that the 
length of the cornicle is often greater (in alate vivipara .60-1.03, in aptera .70- 
1.05-“1.2”) and with reticulated area .20-.30. This is the form referred to by 
Gillette and Palmer (1934:178) as differing only in longer cornicle; but study 
of metatypes and neotypes shows that this character overlaps in range of 
variation so that no exact line of distinction can be drawn. However, since no 
biological evidence as to interchange of host plant has been obtained it seems 
best not to declare the name a synonym. 
Collections. On Aster sp., Chrysothamnus nauseosus subspp. nauseosus and 
viscidiflorus, Gutierrezia sp. and Lactuca sp. Throughout region. Alate and 
apterous viviparae July 15 to Nov. 3, sexuales Oct. 25 to Nov. 12; common. 
