SUBFAMILY APHINAE 123 
Aphis armoraciae Cowen 
The Western Aster Root Aphid 
Aphis armoraciae Cowen (in Gillette and Baker), 1895:117. 
Aphis middletoni1 Thomas*(misidentification), Gillette and Palmer, 1932b:418. 
Apterous Summer Vivipara. Green, yellowish to dusky olive; with powdery reticula- 
tions; dusky on dorsum of head, pronotum, lateral areas of all segments anterior to cornicle 
and bands on all segments, the latter frequently more or less broken or lacking on abdomen 
anterior to cornicle; appendages brownish or dusky except middle of tibiae; cornicle and 
cauda dusky. Body length 1.5-2.5; hind tibia .60-.95; antenna .80-1.1; rostrum hardly attain- 
ing 3d coxa. 
Alate Vivipara. Color as in aptera but dorsal bands more broken or lacking. Body 
length 1.9-2; hind tibia .8-1; antenna 1, secondary sensoria slightly tuberculate. Hairs pointed, 
inconspicuous, shorter than diameter of antenna or hind tibia, drooping and sparse. Cornicle 
with weak flange. Cauda bearing 5-7 hairs on each side. Lateral tubercles quite large on 
prothorax and abdominal I and VII, inconspicuous or absent on other segments. 
Ovipara. Apterous. Color same as in apterous vivipara or darker with hind tibia dusky 
and swollen along entire length and bearing numerous slightly convex sensoria. Body length 
2; antenna .90, III .23, with 3-5 sensoria, IV .13 with 2 sensoria, V .14, VI .12+.16-.20. 
Male. Alate. Color similar to alate vivipara or darker; somewhat smaller. 
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Fig. 130. Aphis armoraciae 
Collections. On roots of Asclepias stenophylla, Ambrosia trifida, horse- 
radish (Armoracia lapathifolia), Artemisia frigida, Aster ericoides, Capsella 
bursa-pastoris, Chicory (Chicorium sp.), Descurainia sp., Erigeron canadensis, 
Helianthus pumilus and sp., parsnip (Pastinaca sativa), dock (Rumex aceto- 
sella) and R. sp., dandelion (Taraxacum officinale), Senecio sp., salsify (Trapo- 
gon pratensis) and corn (Zea mays). Throughout region. Apterous summer 
viviparae May 8 to Oct. 8, alate viviparae May 27 to Oct. 8, oviparae Sept. 27 
to Nov. 6, males Sept. 27 to Oct. 7; very common. 
Type. Lost. Neotype (selected by the author), U.S.N.M. 
Chief Distinguishing Characters. Pale green to olive-green body with 
more or less of broken dorsal bands in aptera, short bushy cauda, usual pres- 
ence of sensoria on the antenna of the aptera, short cornicle (not longer than 
unguis) and male alate, and as compared with A. maidi-radicis: Longer an- 
tenna (III not shorter than .22), more numerous sensoria (usually 10-16, not 
less than 8 on III in alata) and male alate (aptercus in A. maidi-radicis). The 
host plant habits also indicate separate identity, namely: Almost complete 
absence of corn root trouble from this aphid west of the 102d meridian in spite 
of the abundance of said aphid on other plants, and lack of collections on 
cucurbits and grasses which hosts are reported <s readily infested by Aphis 
maidi-radicis. 
The species here treated was formerly determined as A. middletonii 
Thomas but the determination is here changed on account of the probable 
identity of middletonii with maidi-radicis. This status is indicated by descrip- 
