220 APHIDS OF THE ROCKY MOUNTAIN REGION 
Rhopalosiphum pseudobrassicae (Davis) 
The Turnip Aphid 
Aphis pseudobrassicae Davis, 1914a:231; Paddock, 1915:7;: Davis and Satterthwait, 
1916:915. 
Rhopalosiphum pseudobrassicae, Gillette and Palmer, 1932b:487. 
Apterous Summer Vivipara. Olive-green, yellowish to medium; with head, lateral areas 
and two longitudinal dorsal rows of large spots dusky, coarsely reticulated; shining; cornicle, 
cauda and appendages pale to dusky. Body length .85-1.66; across eyes .40-.43; hind tibia 
.63-.90; antenna .95-1.40; rostrum obtuse, attaining 2d coxa. 
Alate Vivipara.. Head and thorax blackish; abdomen dusky green, with blackish lateral 
areas on all segments anterior to cornicles and narrow dorsal bands posterior to cornicles; 
antenna blackish; cornicle, cauda and legs more or less dusky. Body length 1.40; across eyes 
.40; hind tibia .95-1; antenna 1.2-1.55; rostrum attaining between Ist and 2d coxae. Hairs 
blunt, sparse, inconspicuous. Cornicle slightly clavate, with flange and slightly imbricated. 
Cauda tapering on distal half, sometimes nearly parallel-sided, distinctly narrower than 
proximal portion and bearing 2-3 pairs of lateral hairs. Fore wing with 2d fork of media 
short, arising at quarter to third the distance from margin of wing to 1st fork. 
Dither 
Al 
Fig. 257. Rhopalosiphum pseudobrassicae 
Collection. On turnip (Brassica rapa), watercress (Roripa nasturtium 
aquaticum), radish (Raphanus sativa), Capsella bursa-pastoris, and stock (Mat- 
thiola sp.). Colorado: Denver, Loveland, and Fort Collins. Utah: Saint George. 
Wyoming: Wheatland. Alate and apterous viviparae all months of the year; not 
rare and in many cases very abundant and injurious in late summer and 
autumn. 
Cotypes. Davis Collection. 
Chief Distinguishing Characters. Large dark dorsal reticulated areas in 
aptera, absence of noticeable pulverulence, presence of sensoria on IV of alate 
vivipara, length of cornicle (twice or more times length of rostral IV-+-V). 
This species is very close to Aphis erysimi Kaltenbach and may be iden- 
tical. However, Kaltenbach describes his species as with antenna “gekoérnt” in 
apterous vivipara and mentions no rows of dorsal dark spots in aptera. Speci- 
mens determined as erysimi by Hille Ris Lambers agree with Colorado speci- 
mens. Theobald (1927:209), however, states the two species to be distinct on 
account of differences in body marking and in cornicle length. 
Rhopalosiphum rhois Monell 
Monell’s Sumach Aphid 
Rhopalosiphum rhois Monell, 1879:27; Gillette and Bragg, 1915a:100; Gillette and 
Palmer, 1932b:488. 
Amphorophora howardi Wilson, 1911a:59. 
Rhopalosiphum howardi, Davis 1914a:165. 
Apterous Summer Vivipara. Light rusty brown to greenish cadmium-yellow, lighter 
anteriorly and posteriorly; antenna beyond base of III, cornicle, tarsi and tips of tibiae 
blackish to black; legs brownish yellow; cauda pale. Body length 1.9-2; hind tibia .80-.88; 
hind tarsal II .11; antenna 1.25. 
Alate Vivipara. Head and meso- and metathorax dusky; abdomen brownish to greenish 
cadmium-yellow to almost amber, with lateral areas on abdominal I, II, III and IV dark; legs 
dusky to black; cauda concolorous with body; cornicle black; antenna dusky beyond base of 
III. Body length 1.1-1.35; hind tibia .90-.95; hind tarsal II .11-.12; antenna 1.40-1.50, secondary 
sensoria flat, in single row, rostrum obtuse, attaining between Ist and 2d coxae. Hairs slightly 
capitate. Cornicle clavate, width at middle twice that of hind tibia, smooth and with flange. 
Cauda nearly parallel-sided, with slight neck, bearing two hairs on each side and one dorsal 
preapical one. . 
