100 APHIDS OF THE ROCKY MOUNTAIN REGION 
on body a few fine and .03-.04, others heavy .04-.07 and numerous; on hind tibia fine .06-.07, 
nearly erect, length hardly exceeding diameter of tibia. Young. Rusty anteriorly and with 
median dorsal spot on abdomen, remainder of abdomen pale greenish yellow with pale median 
V pattern on thorax. 
Alate Vivipara. Same as aptera except abdomen with dusky bands and lateral spots and 
sometimes appendages slightly longer. Body length 1.5-2. Secondary sensoria on antenna 
circular, with narrow rims. Hairs spinelike and fine; on body .08 long; on hind tibia .04-.05. 
Rostral IV+V .14 hardly attaining 3d coxa. Fore wing with veins heavily bordered with 
smoky; hind wing with veins but faintly bordered; scattered setulae on posterior border of 
stigma. 
Ovipara. Apterous. Head, pronotum, dorsolateral portions of meso- and metanotum and 
abdominal I and median areas of abdominal II to V brown, rest of dorsum pale yellow giving 
effect of pale V; with cornicle bases pale green and with green extending anteriorly near lat- 
eral margin to abdominal I; tibiae pale with black tips except hind tibia which is blackish. 
Body length 2-2.9; hind tibia .75-.80; antenna .95. Hind tibia with proximal seven-tenths 
moderately swollen and bearing numerous sensoria. 
Male. Alate. Head and thorax black; abdomen dark olive-brown with black dorsal bands 
and lateral areas; cornicle yellow; appendages dusky. Body length 1.8; antenna 1.2-1.3, III 
.45, IV .25, V .20, VI .12+.16, sensoria numerous on III, IV and V. Otherwise as in alate 
vivipara. 
Body 
Hairs 
(etetal) 
Fig. 108. Periphyllus populicolus 
Collections. On leaves and twigs of Populus acuminata, P. sargenti and 
P. angustifolia. Throughout region. Fundatrices April 30 to May 23, apterous 
viviparae May 7 to Oct. 23, alate viviparae May 29 to Oct. 20, oviparae Oct. 2 to 
31, alate males Oct. 9 to 31; very common. 
Cotypes. Ill. State Nat. Hist. Surv. Collection, No. 8177. 
Chief Distinguishing Characters. Heavily bordered veins of the fore wing, 
color pattern of the aptera and sinuate anal plate. 
Periphyllus salicicorticis (Essig) 
Symydobtus salicicorticis Essig, 1912a:731. 
Periphyllus salicicorticis, Gillette and Palmer, 1931:925. 
Apterous Vivipara. Head and pronotum dark, mesonotum pale with speckles and lateral 
spots dark, rest of body dingy or greenish yellow or rusty brown with darker dashes and 
lateral spots, dashes often broken, with light area about each cornicle; cornicle and appen- 
dages pale; tips of tibiae hardly dusky. Body 2.3 by 1.3; hind tibia .80-1.1; hind tarsal II .14- 
.16; antenna 1.0, III .30-.37, IV .14-.22, V .14-.18, VI .10-.12+.10 to .13; cornicle .07-.10; cauda 
.07. Rostral IV+V .25, attaining middle of abdomen. Hairs simple, of two kinds; on body 
and vertex, some spinelike .12-.15 long and others fine .05-.06; on antenna fine .03-.05 (diameter 
of antennal III .03); on hind tibia fine .05-.06 long. 
Alate Vivipara. Measurements same as apterous vivipara or slightly larger. Head and 
thorax blackish; abdomen pale dingy green with dorsal dashes and lateral areas. Body length 
1.5-2.3; hind tibia .9-1; antenna 1.4, III .40-.48, IV .21-.26, V .20-.23, VI .12-.14+.11-.16, sec- 
