370 APHIDS OF THE ROCKY MOUNTAIN REGION 
Key to Species of Thecabius 
(Based on alate viviparae from galls or pseudo galls) 
1. WI with secondary sensoria’ in fundatrigenia -2..----.<c---: cscs cece ge cececencecnceetegec=censdeee eee eee nee 2 
.-- WI without secondary sensoria in fundatrigenia ............----...---.-::e---eseeececceneeecceeeecenneesenececeeeeeeneey 3 
2. In America. Alate fundatrigenia with 5-8 secondary sensoria 
Foye U RB Gs 1/40) Peaeceeste thao ee pelea tocar Paes Ean a eee a ie et Aa a ib populi-conduplifolius 
In Europe. Alate fundatrigenia with 3-4 secondary sensoria on VI. (p. 370)............ affinis 
3. Sensoria-on IIT more: than 10: (p03 70) 2.eiosccccscncan-ccevgsnceccoceyeteeescenntsaageteseoee-sroreeee eee gravicornis 
Sensoria on [ll fewer thane 0) (75371) feccceeeerrrrce acest populi-monilis 
[Genotype Thecabius affinis (Kaltenbach) ] 
Pemphigus affinis Kaltenbach, 1843 :;182. 
Thecabius affinis, Tullgren, 1909:103; Mordvilko, 1935:62. 
Characters. Similar to T. populi-conduplifolius; apparently differing only 
by character given in key. (Decision based on description by Tullgren and 
specimens determined by van der Goot and Hille Ris Lambers.) (Not taken in 
region.) 
Thecabius gravicornis (Patch) 
The Folded-leaf Balsam Aphid 
Pemphigus gravicornis Patch, 1913:75. 
Thecabius gravicornis, Maxson, 1923:325; Gillette and Paimer, 1934:234. 
Fundatrix. Head and pronotum dark; rest of body pale honey-yellow; appendages and 
rostrum dark. Body length 2; antenna .52. 
Alate Fundatrigenia. Head and thorax brown; abdomen olive-yellow; appendages and 
rostrum brownish to black. Body length 1.7-2.8; fore wing 3-3.5; hamuli 2 in number; hind 
tibia .75-.85; hind tarsal II .23; antenna 1.05-1.27, secondary sensoria very broad and often 
more or less annular. Rostrum attaining 2d coxa. 
: Galls Fundatryg, Fund 
x “ AS R. és Ca, 
oy Ops, * 
u 10-., yas 
Alate PANY) DN D=aUAD ANN Cee Aecdth ANNA Mesothoraci 
Fund.at r\geni J Mevaal aD mi Lae 7g) (22-27Nsen@-S) 15-18) +05 “jiands 
Fig. 447. Thecabius gravicornis 
Pseudo Galls. Fundatrix in small pocketlike swelling on upperside of leaf about halfway 
between midrib and edge of leaf, opening on under side; progeny on underside of leaves which 
are folded downwards together on midrib. 
Collections. As winter host on Populus tacamahaca, in folded leaf pseudo 
galls. Colorado: Pennock Pass (above Masonville), Steamboat Springs and at 
Red Feather. Fundatrices Aug. 24, alate fundatrigeniae Aug. 18 and 24; rare, 
perhaps on account of rarity of host. 
Chief Distinguishing Characters. Unusually broad, transverse, approxi- 
mately annular secondary sensoria, character of the pseudo galls, absence of 
sensoria on VI and short antenna of fundatrix (III not longer than about .15). 
Thecabius populi-conduplifolius (Cowen) 
The Folded Leaf Poplar Aphid 
Pemphigus populi-conduplifolius Cowen (in Gillette and Baker), 1895:115; Jackson, 
1908 :217. 
Pemphigus ranunculi Davidson (W. M.), 1910:372. 
Ferphigus californicus Davidson (W. M.), 1910:374 and 1911b:414; Essig, 1912a:699 
and 700. 
Thecabius populi-conduplifolius, Gillette, 1914b:61 and 1915a:99; Maxson and Knowl- 
ton, 1929:252; Gillette and Palmer, 1934:234; Mordvilko, 1935:68. 
Fundatrix. Slaty-gray to yellow-olive-green, black on head; powdery with lateral and 
terminal threads; rostrum and appendages blackish. Wax plates on head, 3 pairs dorsal and 
one pair ventral, largest pair on posterior portion; on pronotum a row of 4 large ones near 
posterior margin and anterior to these a median pair of smaller ones, one or both of which 
may unite with the larger ones, leaving a total of either 4 or 5 on this segment; remainder of 
body with 6 longitudinal rows to abdominal VII where the number becomes 4 again. Body 
length 3.75-4.25; hind tibia .55-.80; hind tarsal II .17-.20; antenna .70-.80; rostrum attaining 2d 
coxa. 
