58 APHIDS OF THE ROCKY MOUNTAIN REGION 
fine and .05 long; on antennal III fine and sparse; on hind tibia fine, slightly longer than 
diameter of tibia. Cornicle a mere rim on slightly raised base which latter bears about 4 fine 
hairs. Cauda knobbed; anal plate entire but with appearance of median depression. Lateral 
tubercles small, evident on prothorax. 
Alate Vivipara. (Mounted on slide), head and thorax blackish; antenna, rostrum, corn- 
icle, lateral areas on abdomen and legs more or less dusky; cauda and anal plate pale to 
slightly dusky. Body length 1.2; across eyes .30-.32; antenna .55-.60; hind tibia .50; hind 
tarsal II .09; rostrum with tip beyond hairs parallel-sided, resembling distinct segment V, 
attaining 2d coxa. Cornicle shallow-conical, bearing a few simple hairs. Cauda knobbed, bear- 
ing 2 pairs of lateral and 2 pairs of dorsolateral hairs and a single preapical one. Fore wing 
with media once-branched; hind wing with a single cross-vein. 
Ovipara. Apterous. (Mounted on slide), immaculate; appendages pale, to slightly dusky, 
especially distally. Body length .70; across eyes .22; antenna .30; hind tibia slightly swollen 
and bearing a few faint, scattered sensoria especially on proximal half. Rostrum with needle- 
like tip beyond hairs inconspicuous. Cornicle and cauda as in viviparae. Hairs heavy and 
spikelike on body with occasionally one pair of fine ones on vertex. 
Hd Tin 
Oy 
Sa 
Hd.Tib. 
soe 
Fig. 57. Thelaxes californica 
oe, 
Sele aes 
een) DpaY 
gen.) -fl-13 
Collections. On Quercus sp. Colorado: near Gateway. Utah: Thistle and 
Castle Gate. Apterous viviparae June 9 and 29, alate viviparae June 27 and 29, 
oviparae Sept. 29 to Oct. 11; somewhat common in Utah. 
Distinct status of this form from T. dryophila is doubtful, considering the 
variations in apterous viviparae of the latter obtained from various workers. 
The only difference discovered is the smaller number of sensoria on antenna 
of alate vivipara. 
[Genotype Thelaxes dryophila (Schrank) ] 
ALP, Vent ral Aspect 
A pt. Body 
KET 
Nee Hairs OES 
: 05> 
—_— 
025 
t RYT TTF fags 
0-16 1-18 .03-02 
04 Wd, 00405 
05 Ta RRS, 5 ar 
Fig. 58. Thelaxes dryophila 
Aphis dryophila Schrank, 1801:113. 
Thelaxes quercicola Westwood, 1840:118. 
Thelaxes dryophila, Buckton, 1883:8. 
Vacuna dryophila, Tullgren, 1909:36; van der Goot, 1915:422; Theobald, 1929:73. 
