206 APHIDS OF THE ROCKY MOUNTAIN REGION 
Genus Microsiphum Cholodkovsky 
Cholodkovsky 1908:687; Baker, 1920a:49. 
Characters. Frontal tubercles moderately developed but not markedly ex- 
ceeding vertex. Secondary sensoria circular. Cornicle not longer than broad 
at base, truncate or short-cylindrical or narrowed at the base. Cauda broader 
than long, tapering, bearing numerous hairs. Fore wing with media twice- 
forked. Hairs simple. 
Genotype (monotypical), Microsiphum ptarmicae Cholodkovsky. 
Key to Species of Microsiphum 
1. 'Cauda bearing about 6 pairs of lateral hairs (p., 208))cccceccccc ee cee teens eee eee ptarmicae 
.. Cauda, bearing: distinctly fewer thani6 pairs of shairs.cc--sscccse rca eneeee een ee 2 
2.. “Body bearing-blunt to fan-shaped hairs (p.207)nccce--ces cen en ne sence cece caeeeeespeae eee ee oregonensIs 
2. - Body: not! bearing fan-shaped hairs -ccc)cc2oooco soo oc acces oe ncten cose sever seats sso ccapeeeg ee 3 
3... Uneguis' 5-6 times lengthsof base of, Vi (ps 207) secret sence econ artemisiae 
Unguis shorter than five times length of base of VI (p. 206)........-....-2.-0--.:--000---e00- acophorum 
Microsiphum acophorum Smith and Knowlton 
Microsiphum acophorum Smith and Knowlton, 1938:162. 
Apterous Summer Vivipara. ‘‘Shiny brownish black to black on dorsum,”’ which also 
appears dark in cleared and mounted specimens, which latter show venter colorless except 
dark patch on abdominal VIII, dark color on coxae, trochanters, femora, especially 2d and 3d 
pairs, tips of tibiae, entire tarsi, antennal I and II, tip of IV, more or less of V and entire VI 
and rostrum; cauda, anal plate, genital plate and cornicle pale to slightly dusky. Body length 
1.03-1.45; across eyes .34-.35; antenna 1.10-1.63; hind tibia .50-.85; hind tarsal II .10-.125- 
**14”’; rostrum attaining 3d coxa or abdomen. 
S S aco 020-000 a. Ae Species ’ 
ad T30°.35°88 .25 -.30-"40" "45% .26 IPS\2, “35738 -45 359" 
Fig. 239. Microsiphum acophorum 
Alate Vivipara. Black; antenna dark. Body length 1.25-1.43; antenna 1.38-1.50; hind 
tibia .78-.84; hind tarsal II .14; rostrum attaining abdomen. Cornicle cylindrical or slightly 
broader at base, smooth and with flange. Cauda tapering, acute, shorter than broad, bearing 
2 pairs of lateral hairs. 
Ovipara. Apterous. ‘Shiny brownish black.’’ (Cleared and mounted on slide), dark 
markings as follows: Head, dorsal bands on abdominal VII, dorsal and ventral bands on 
VIII, lateral spots on abdominal I to VIII; coxae, trochanters and femora especially 3d pair, 
knees, swollen portion of hind tibia, tips of tibiae, entire tarsi, entire antenna though paler on 
III, cauda, cornicle and rostrum, especially distally. Body length 1.3-1.4; across eyes .34; 
antenna 1.1-1.6; segments as in apterous vivipara; hind tibia .55-.63 long, proximal third dis- 
tinctly swollen and bearing about 12 large sensoria. 
Male. Alate. Greenish brown; antenna blackish; legs and rostrum dusky; cornicle pale 
to dusky. Body length 1.10; across eyes .34; antenna 1.5-1.6; hind tibia .65-.75; hind tarsal II 
-11-.12; rostrum attaining abdomen. 
Collections. On Artemisia tridentata and A. longifolia. Colorado: Craig. 
Utah: Throughout northern part of the state. Wyoming: Chimney Rock (near 
Jelm). Idaho: Whitney and Thousand Springs. Apterous viviparae May 19 to 
Sept. 3, alate viviparae July 7, sexuales Sept. 11 to Oct. 9, eggs Oct. 7; somewhat 
common. 
Type. U.S.N.M. Paratypes, C. F. Smith, Knowlton and Colo. Agr. Exp. Sta. 
Collections. 
Chief Distinguishing Characters. Pointed hairs on vertex and length of 
unguis (shorter than five times base of VI). 
