190 APHIDS OF THE ROCKY MOUNTAIN REGION 
Genus Atarsos Gillette 
Gillette, 1911a:440; Baker, 1920a:44; Gillette and Palmer, 1932b:458. 
Characters. Frontal tubercles rudimentary. Antenna six-segmented, much 
shorter than body, secondary sensoria circular, numerous on III, IV and V. Hairs 
capitate. Both segments of tarsus entirely lacking on all legs and in all stages, 
tibiae ending in the ordinary pulvillus. Cornicle cylindrical with sudden con- 
striction forming an encircling groove next to flange. Cauda tapering to a point. 
Fore wing with media twice-branched; hind wing with both media and cubitus 
present. 
Genotype (monotypical), Atarsos grindeliae Gillette. 
Chief distinguishing character is the absence of both segments of the tarsi 
on all legs in all forms. Mastopoda Oestlund lacks only tarsal II, has cornicle 
without flange and narrowed in middle and antenna is five-segmented. 
Only one species represented in region. 
Genotype Atarsos grindeliae Gillette 
The Footless Grindelia or Gumweed Aphid 
Atarsos grindeliae Gillette, 1911a:440; Gillette and Palmer, 1932b:459. 
Fundatrix. Color and measurements as in summer apterous vivipara except the following: 
Body length 1.30-1.80; hind tibia .80-.85; antenna .80-.85, III +I1V (coalesced) .32-.35, V 
.12-.13, VI .10-++.10, secondary sensoria 11-14 on III+IV, 0-2 on V; cornicle .18. Otherwise 
as in summer aptera. 
Apterous summer Vivipara. Pale yellow to pale green, shining; antenna, cornicle and 
tibiae pale proximally, black distally. Body length 1.05-1.55; hind tibia .50-.72; antenna .72- 
1.05; rostrum attaining between 2d and 3d coxae. 
Alate vivipara. Head and thorax black; abdomen pale yellow to pale green: shining; with 
faint broken dusky dorsal dashes and lateral areas; appendages pale proximally to dusky 
distally; venation of wings rather heavy. Body length 1.6-2; hind tibia .80; antenna 1.12, 
secondary sensoria tuberculate, rostrum hardly attaining 2d coxa. Hairs capitate. Cornicle 
cylindrical, smooth, with distinct flange and with collarlike depression just before flange. 
Cauda tapering, acute, hardly longer than broad, bearing 2 pairs of hairs on each side and a 
single dorsal preapical one. 
Ovipara. Apterous. Yellowish green shading to brown on head and tip of abdomen; 
shining; antenna dark brown; cornicle and tibiae light brown to dusky. Measurements as in 
summer apterous vivipara. Hind tibia slightly swollen on proximal half and bearing about 18 
rather large sensoria. 
Male. Apterous. Color same as in ovipara. Body length .90; hind tibia .40-.50; antenna 
.55-.55, III and IV coalesced. 
Egg. Newly laid, colorless; later, black; shining. Length .60, width .30. 
Collections. On leaves of Grindelia squarrosa and Aster leucanthemifolius. 
Colorado: Fort Collins. Fundatrices April 16 to May 11, apterous summer vivi- 
parae April 26 to Aug. 22, alate viviparae May 3 to June 23, sexuales Sept. 29 to 
Oct. 24; rather common. 
Type. U.S.N.M., No. 41932. Paratypes, Colo. Agr. Exp. Sta. Collection. 
Genus Brachycolus Buckton 
Buckton, 1879:146; Baker, 1920a:45. 
Characters. Body long and narrow. Vertex rather flat; frontal tubercles not 
developed. Cornicle very short hardly more than a pore. Antenna six-seg- 
mented; secondary sensoria circular. Legs short; tarsal II rather long. Fore 
