SUBFAMILY ERIOSOMATINAE 357 
well developed, composed of small polygon and often irregularly shaped patches, surrounded 
by a distinct chitinous margin and often armed with a few or more long bristles; a pair of 
plates on mesonotum; on abdominal I to VII normally 4 longitudinal rows but dorsal rows 
often joined and on abdominal VIII only two plates. Body length 3.8; antenna 1.5; hairs on 
antenna very sparse; hind tibia 1.52; hind tarsal II .39; fore wing 5.3, media once-forked. 
Biology. Living on Populus tremula, fundatrix on bark of young twigs, 
fundatrigenia on leaf petioles which their feeding distorts so as to cause a sharp 
bend at the junction with the leaf and clustering of otherwise normal leaves. 
During July alatae develop and fly away so that by August practically none 
remain. Summer host is unknown. 
The above description and figure were adapted from figure and description 
by Tullgren (op. cit.). (Not taken in region.) 
Genus Cornaphis Gillette 
Gillette, 1913:491; Gillette and Palmer, 1934:219. 
Characters. Vertex produced, in summer vivipara forming a horn, in alata 
forming a raised base for the ocellus; frontal tubercles lacking. Cornicle pres- 
ent as a mere ring or absent. Antenna five-segmented in fundatrix, six-seg- 
mented in alata, secondary sensoria narrow-oval and transverse. Cauda semi- 
lunar. Media of fore wing simple; hind wing with both cubitus and media. Wax 
plates composed of many equal facets surrounded by a ring, present in sum- 
mer aptera. Sexuales apterous and without rostrum. 
Living in pseudo galls on leaves; fundatrix in same gall as progeny. 
Genotype (monotypical), Cornaphis populi Gillette. 
Genotype Cornaphis populi Gillette 
The Crescent-gall Poplar Aphid 
Cornaphis populi Gillette, 1913:491; Gillette and Palmer, 1934:219, 
Fundatrix. Slaty-gray with head black and 4 spots on pronotum; powdery; appendages 
black. Body length 2.75; hind tibia .31-.35; hind tarsal II .10-.12; antenna .40; rostrum at- 
taining between 2d and 3d coxae. Wax plates absent. Cornicle not evident. 
ichen agi mee 
Fig. 429, Cornaphis populi 
Apterous Vivipara. Fundatrigenia. Light straw-yellow with head and 4 patches on pro- 
notum black; powdery; appendages dusky. Body length 2-2.25; hind tibia .40-.50; hind tarsal 
II .13-.15; antenna .58; rostrum attaining 3d coxa. Cornicle mere ring. 
Alate Vivipara. Sexupara. Head and antenna dusky; thorax brownish; abdomen pale 
greenish yellow. Body length 2-2.25; fore wing 2.75; hind tibia .70-.85; hind tarsal II .18-.20; 
antenna .74-1; rostrum attaining between Ist and 2d coxae. Cilia on permanent sensoria weak. 
Cornicle not evident. Fore wing with media simple. 
Ovipara. Apterous. Yellowish green; appendages pale. Body length .60; antenna .17, 
five-segmented, III .03, IV .03, V .04-.05+.01; hind tibia .07. Rostrum missing. 
Male. Apterous. Darker and much smaller than female. Rostrum missing. 
Collections. On Populus augustifolia in pale or red-streaked podlike pseudo 
galls composed of folded edges of leaves. Colorado: Monte Vista, South Saint 
Vrain Canyon and Fort Collins. Wyoming: Laramie. Fundatrices June 25, apter- 
ous summer viviparae and alate sexuparae July 10 to 15, sexuales July 15; rare. 
Fundatrix, apterous fundatrigeniae and sexuparae all develop in the same gall. 
Type. U.S.N.M., No. 42815. Paratypes, Colo. Agr. Exp. Sta. Collection. 
