SUBFAMILY APHINAE 151 
8, alate viviparae June 26 to Oct. 6, oviparae Sept. 8 to 28, males Aug. 24 to 
Sept. 10; viviparae and alate males all taken on Populus, oviparae on Cornus; 
infestations rare, but in large numbers where found occurring. 
Cotypes. Univ. of Minn. Collection. 
Aphis maidi-radicis Forbes 
The Corn Root Aphid 
Aphis maidis Fitch(?) (misidentification), Weed, 1887 and 1888:70. 
Aphis maidi-radicis Forbes, 1891:64 and 1894:58; "Garman, 1898:177 (desc. of ovipara) ; 
Webster, 1907:4 (desc., habits and control) ; Davis, 1909b:123 (life hist. and 
bibliog. to date); Vickery, 1910:97 (acct. of extensive experiments); Gillette and 
Palmer, 1932b: 414, 
Apterous Summer Vivipara. Pale bluish green with more or less dusky markings on 
head, pronotum, lateral areas and narrow or broken dorsal bands on meso- and metanotum and 
abdominal I, VII and VIII; antenna, cornicle, rostrum, cauda and anal and genital plates 
dusky; legs dusky except middle of tibiae. Body length 1.80; hind tibia .80; hind tarsal II 
.10; antenna .70; rostrum attaining 3d coxa or abdominal I. 
rae 
Ova MAINDN HONS? a 
"20-24 .09-1 08-1 09- ae Ga eo < 
opied utter Ferhed 
Fig. 168. Aphis maidi-radicis 
Alate Vivipara. Head and thorax black; abdomen pale green, with lateral areas anterior 
to cornicles, patch posterior to base of each cornicle and short dorsal bands on abdominal VI, 
VII and VIII dusky. Body length 1.50; hind tibia .70; hind tarsal II .10; antenna .70, sec- 
ondary sensoria hardly tuberculate, in single row; rostrum attaining between 2d and 3d coxae. 
Hairs pointed, inconspicuous, drooping and sparse; .01-.02 long on antenna, body and hind 
tibia. Cauda broadly tapering, rounded at tip, bearing about 6 hairs on each side. Lateral 
tubercles developed on prothorax, and abdominal I and VII, inconspicuous or absent on other 
segments. 
Male. Apterous according to Davis (op. cit.), Weed (1888:70), Forbes (op. cit.), but 
alate according to Vickery (op. cit.). 
Collections. On roots of Artemisia frigida and A. aromatica, Aster sp., 
Helianthus sp., Descurainia sp. and corn (Zea mays). Colorado*: Julesburg, 
Sedgwick, Lamar and Denver. Utah: Farmington, Roosevelt, and Castle Valley. 
Idaho: Riverdale. Apterous viviparae June 8 to Aug. 11, alate viviparae Aug. 
20; rather rare. No serious damage to corn reported west of the 102d meridian. 
Chief Distinguishing Characters. Bluish green bsdy with slight dashes, 
short antenna (III .24), short cornicle (.14 in alata, .20 in aptera), few sensoria 
on III (8), short, bushy cauda and long rostral IV+-V (.14-.15). 
This species appears structurally very close and doubtfully separable from 
A. middletonii Thomas. Perhaps it should be placed as a variety. However, 
more biological tests should be carried out to decide the question. 
The study of this species was greatly aided by the examination of more 
than two dozen slides, labelled A. maidi-radicis and A. middletonii determined 
by several aphidologists, loaned by T. H. Frison and H. H. Ross also one or 
two slides contributed by Geo. G. Ainslie collected in work in cooperation 
with Vickery (op. cit.). 
Aphis medicaginis Koch 
The Cowpea Aphid 
Aphis medicaginis Koch, 1854:94; Essig, 1911c:527; Gillette and Palmer, 1932b:416. 
Aphis laburni Kaltenbach (misidentification), Theobald, 1927:122; Hille Ris Lambers 
1934:27 (criticism on A. Jaburni Kaltenbach according to Theobald). 
*Statement by Gillette (1910:405) that this species is fairly common on corn at Fort 
Collins evidently refers, at least in part, to A. armoraciae as shown by the drawings 
and hosts given as well as slides of those dates in the collection. No serious corn root- 
aphid injury has attracted attention at Fort Collins. 
