188 APHIDS OF THE ROCKY MOUNTAIN REGION 
1.3; hind tibia .70-.73; rostral IV+-V slender .114, attaining 2d coxa. Lateral tubercles present, 
more noticeable on prothorax and abdominal I and VII. Cauda slightly tapering, bearing 3 
hairs on each side. 
Collections. On Salsola sp. Utah: Thompsons. Alate viviparae Sept. 13. 
Type. U.S.N.M. 
This species differs from A. pruni as follows: Sensoria on III fewer than 10 
and absent on IV and hairs on antenna sparse and practically invisible. 
Genus Aspidaphis Gillette 
Gillette, 1917c:196; Baker, 1920a:44; Gillette and Palmer, 1932b:456. 
Characters. Vertex strongly convex; frontal tubercles distinctly produced, 
fully equal with vertex. Antenna five-segmented; secondary sensoria circular. 
Cornicle clavate, recumbent, without flange, and with opening placed laterally 
on median side of distal end. Lateral tubercles absent. Hairs very inconspicuous. 
Tergite VIII forming triangular shield extending over cauda. Wing venation 
as in genus Aphis. 
Genotype (monotypical), Aspidaphis polygoni Gillette (syn. of Aphis adjuvans 
Walker). 
Key to Species of Aspidaphis 
1. Length of hind tibia .85 or longer; sensoria 14 on III in alata (p. 189)...................... aquatica 
... Length of hind tibia shorter than .85; sensoria fewer than 14 on III of alata................ ..... 2 
2." (On Poly zonuirn: (pi 188). oceces i akcncsccdcoosse ce acenesoaade cevapsenectoadne went coat eeyes saat he gee ete eiiivans 
On Chrysothamenus: (pp. 189): (oi cco0c neces icceystopsevaresBavevenedpacnapenberest sons crepe btasieanetbn ose ane ann var. rowel 
Genotype Aspidaphis adjuvans (Walker) (synonym, polygoni 
Gillette) n. syn. 
The Armoured Knotweed Aphid 
Aphis adjuvans Walker, 1848b:2220. 
Aspidaphis adjuvans, Laing, 1921:125; Theobald, 1927:310. 
Aspidaphis polygoni Gillette, 1917c:196; Gillette and Palmer, 1932b:456. 
Apterous Summer Vivipara. Pale yellow to pale bluish green; all appendages pale with 
tips of segments blackish. Body length 1.5-2; hind tibia .35-.50; hind tarsal II .12; antenna 
.35-.50. Dorsal surface of body rugose. Tergite VIII developed into large triangular shield 
extending well beyond the end of the cauda. 
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Fig. 218. Aspidaphis adjuvans 
Alate Vivipara. Head and meso- and metathorax dusky brown; antenna and tarsi black- 
ish; cornicle and cauda pale. Body length 1.4-2; hind tibia .55-.77; hind tarsal II, .12-.14; 
antenna .58-.85, III and IV coalesced; rostrum broadly obtuse, attaining between Ist and 2d 
coxae. Hairs blunt, minute and sparse. Eye without ocular tubercle. Cornicle clavate without 
flange, with opening on median side slightly before tip, smooth, recumbent against body, 
weak, hardly wider than antennal III. Cauda tapering acute, bearing 3 straight, short hairs 
-02 on each side. Lateral tubercles absent. Tergite VIII projecting about as far as tip of 
cauda. 
Ovipara. Apterous. Color brownish or slightly rusty. Slightly shorter and more robust 
than apterous vivipara; otherwise the same. Hind tibia moderately swollen along middle and 
bearing 20 or more large, circular. rather flat sensoria. 
Egg. Newly laid, bright green; later, black; shining. Size .73 by .26. 
Collections. On underside of leaves of Polygonum aviculare. Colorado: 
Fort Collins and Boulder. Apterous summer viviparae April 27 to Oct. 10, alate 
viviparae June 19 to Aug. 4, oviparae Oct. 6; common. | 
Type. Aspidaphis polygoni Gillette, U.S.N.M., No. 41931. Paratypes Colo. 
Agr. Exp. Sta. Collection. 
