SUBFAMILY ERIOSOMATINAE 349 
Collections. On winter host, in bladderlike galls on upperside of leaves of 
Ulmus campestris; on summer host, on roots of Agroypron sp. and other grasses. 
Colorado: Cherokee Park and Fort Collins. Fundatrices on elm May 7 to June 
20, hiberating viviparae in ants’ nests and on grass roots April 2 to May 24, sum- 
mer apterous viviparae on grass roots throughout the summer, alate viviparae 
on elm (fundatrigeniae) June 27 to July 12 and (sexuparae) Aug. 31 to Nov. 4 
and on grass June 29 to Oct. 8, sexuales Sept. 19; common. 
Genus Eriosoma Leach 
Leach, 1818:60; Baker, 1920a:66; Davidson (J.), 1925:101. 
Characters. Vertex convex; frontal tubercles lacking. Antenna five-seg- 
mented in fundatrix and sexuales, six-segmented in summer viviparae; second- 
ary sensoria annular. Wax glands present on viviparae; composed of facets 
surrounding a center. Cornicle distinct ring on slightly mammiform base. Cauda 
and anal plate rounded. Hairs pointed, very short and inconspicuous. Fore wing 
with media once-branched; hind wing normally with both media and cubitus. 
Living in pseudo galls or on roots or exposed on plants but covered with waxy 
secretion. 
Genotype (monotypical), Aphis lanigera Hausmann. 
Key to Species of Eriosoma 
1. III shorter than IV+-V+VI in alate and apterous viviparae. In rolled leaves of 
UlImus americana and on roots and leaves of Amelanchier sp. (p. 349).......--..--- americanum 
III not shorter than IV+V-+VI in alate and apterous Viviparae..............-:...:c-:c2eceeeeeeeeeeeeess 2 
2. Media of fore wing with fork distinctly distad of origin of radial sector. 
CREE SE ay PSP PORTS LAW USN TE IE MENS Sha te gach Se eet a a eee el Oe rileyi 
... _ Media of fore wing with fork not distinctly distad of origin of radial sectot...................-.. 3 
BREETISOEL ANON DV GEAHOR( DGD) Steere tre eet cate eae as ere ee pau rack shoe Si natns ies avausencdsdesensesetenenrceaecees Janigerum 
... Sensoria on V, 6-10. On bark of branches of Crataegus (p. 350)........-.--.::---s-+eeeeeeseeees crataegi 
Eriosoma americanum (Riley) 
The Woolly Elm Aphid 
Schizoneura americana Riley, 1879:4. 
Eriosoma americanum, Patch, 1915:197; “Maxson, 1923:313; Gillette and Palmer, 1934: 
2115 
Fundatrix. Sordid amber to mottled olive-green to blackish; darker on head, cauda and 
anal and genital plates; woolly; appendages and rostrum pale yellowish to dusky. Body 
length 2.4-3.0; hind tibia .45; hind tarsal II .13; antenna .50-.54; rostrum attaining between 2d 
and 3d coxae. Cornicle not evident. 
TUTOR 
vv. 33--50) (ser. 23- 20 
A tes gen) .35-.39 
Viv “& Eye % 
Fig. 419. Eriosoma americanum 
Apterous Summer Vivipara. Fundatrigenia (on elm). Pale with head and anal and gen- 
ital plates black or blackish; rostrum and appendages dusky except lighter on antennal ITI. 
Body length 2.30; antenna 1.03; hind tibia .75; hind tarsal II .20; rostral IV+V .15, attaining 
2d coxa. Cornicle mere pore or slightly raised rim on slightly raised base which is surrounded 
by a row of hairs. ; 
Alate Vivipara. (On Elm). Dark green to slaty-black; woolly; head, thorax, cauda and 
anal and genital plates, appendages, cornicle, rostrum, stigma and costal and subcostal 
veins black or blackish. Body length 2-2.5; hind tibia .8-1.2; hind tarsal II .16-.22; antenna 
1-1.26; fore wing 3-3.8; rostrum attaining 2d coxa. Wax glands evident as circles surrounding 
a central space. Cornicle mere rim surrounded by slightly raised base which is surrounded 
by a ring of short spinelike hairs. 
Apterous Summer Vivipara. (On Amelanchier). Light pink; woolly. 
