374 APHIDS OF THE ROCKY MOUNTAIN REGION 
Collections. Primary host, Pistacia sp.* (not occurring naturally in North 
America); secondary hosts, roots of Agropyron sp., Bromus inermis and B. 
tectorum, Echinochloa crusgalli, Elymus sp., Hordeum sp., Kentucky bluegrass 
(Poa pratensis), Setaria sp., barley, oat and wheat and in ants’ nests. Colorado: 
Generally in northeastern part of state on plains and foothills, also at Fort 
Lewis. Utah: Mount Timpanogos. Apterous viviparae all months of the year, 
alate viviparae June 10 to Aug. 21; very common, often quite injurious. 
Type. U.S.N.M. 
Apt.Viv. 
Nyaa ek 
a alya aa. 
Seine apc 3 433%) 
oa eed gah 
Apt (16-25) 08-10) (0974) 3 
Sen. 11-2 
0900 0.99090. Xa > 
masemee ee ahh 
Fig. 451. Forda olivacea 
This species appears to be very close if not identical with F. marginata 
Koch, judging the latter species from Koch’s description of the apterous vivi- 
para, Vayssiere’s (Theobald, 1929:189) brief description of alate vivipara and 
from examination of apterous viviparae sent by Hille Ris Lambers from Hol- 
land. However, Mordvilko (1935:164) has a different conception of Koch’s 
species and considers Forda follicularia (Passerini) as very close. More in- 
formation is necessary before the synonymy can be decided. 
Genus Geoica Hart 
Hart, 1894:101; Baker, 1920a:79; Maxson 1923:318. 
Characters. Antenna four- or five-segmented in aptera, five- or six-seg- 
mented in alata, I and II coequal in length, IV short and thick; secondary sen- 
soria oval, permanent sensoria ciliated. Eye in aptera consisting of ocular 
tubercle only. Cauda semilunar.** Cornicle lacking. Fore wing with media 
simple; hind wing with both media and cubitus. Living subterranean on roots 
and attended by ants. 
Genotype (monotypical), Geoica squamosa Hart [synonym of Geoica utricu- 
laria (Passerini) ]. 
Genotype Geoica utricularia (Passerini) 
Pemphigus utricularius Passerini, 1856 :260. 
Geoica pacar. Hart, 1894:101; Hottes and Frison, 1931a:356; Gillette and Palmer, 
1934:239. 
Hairs 
» Anal 
Plate-~ 
~ 
~ 
~ 
Side View 
A Side View. Tip of Abdomen 
Fig. 452. Geoica utricularia 
*According to Mordvilko (op. cit.) who considers his wilsoni which infests Pistacia as 
primary host to be the same species as olivacea. 
**The unusually large rectangular anal plate has evidently been mistaken for the cauda 
by several writers who have described the cauda as “large and rectangular.” In live 
aphids observed for determining this point a drop of honeydew was extruded dorsad 
to the rectangular plate, as indicated in figure. 
