110 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
FIELD KEY TO THE APHIDS, BASED PRINCIPALLY ON HOST PLANTS—Continued 
18 (16). Causing conical galls on upper surface of leaves. Insects 1 to 2 
mm. long, color pale yellowish to greenish_- Hormaphis (p. 138). 
Causing spiny galls from buds on stems. Insects 1 to 2 mm. 
long, color pale yellowish to greenish___ Hamamelistes (p. 188). 
19. A).5 sO COMETS. 2 = 22 a eee 20 
On hardwoods 2 022 2 Se Se re eee 29 
20°:(19).-Om pimes oe ea Seer a ae er eh 21 
On other conifersyaas Se 8 oe Rie a a gee eo a 24 
21 (20). Small, dark insects covered with white flocculence. Occurring 
on trunks and branches of Austrian, Scotch, and white pine. 
Pineus strobi (Hartig) (p. 138). 
Insects not covered with white flocculence, at most pruinose. 
Occurring on twigs branches ,Ormeavies asses ae eee 22 
22 (21). Color shining black with white powdery spots on sides and white 
median dorsal line; legs black; body hairy, hairs long and stiff. 
On branches and twigs of white pine_ Cinara strobi (Fitch) (p.128) 
Notas aboves 2.225 2o 2 ae ee Se oe eae Ee ee eee ee 23 
23 (22). Color olive brown, body hairs sparse and spinelike. On leaves of 
Scotch, ponderosa, shortleaf, and white pine. 
Eulachnus rileyi Wms. (p. 127). 
Color pale green with white pruinosity. On leaves and twigs. 
Mindarus abietinus Koch (p. 133). 
QA (DO Va Organ chy Tee I RY Sk Te ag al cme peep ee 25 
On other-conifersi#@22t= os ok Bee a ee ee ee 26 
25 (24). Color dark brown to black with brown spots on abdomen, legs 
mostly black; about 38 mm. long. On twigs and around base of 
IE AVESE = lake Senet. Rien 2 Cinara clarieissaQWike)) Gos ek27)e 
Appearing as white woolly masses on the needles, as dark indi- 
viduals on the underside of twigs, or as clusters of dark indivi- 
uals at the base of the leaves. Chermes strobilobius Kalt. (p. 187). 
26 (24). Nymphs dark green in color. On Douglas-fir, often causing ab- 
norm alsfolageidrope.e ss. see = Chermes cooleyt Gill. (p. 185). 
NOt 78S ab Ove so elec We Es Ne PRT G7 is rey gh oink VN gee 27 
27 (26). Color cinnamon brown with 4 rows of black spots on abdomen; 
length about 3 mm.; many specimens covered with fluffy white 
wax above; body hairs long and fine. On black spruce branches 
FEW la Paid eas besipe oath ae ge aad a Cinara abietis (Fitch) (p. 127). 
ING BS BID OVC Saye Bee Se Ee ae is eee roe 28 
28 (27). Color brownish black with a slight pruinosity, legs brown to black, 
antennae pale: length about 5mm. On branches, twigs, stems, 
and roots of firand Atlas cedar___Cinara curvipes Patch (p. 127); 
Color pale green with pruinosity, or with white flocculent covering 
when on balsam fir; length about 2mm. On fir and spruce 
twigs and leaves, causing curling and roughening of twigs 
Mindarus abietinus Koch (p. 133). 
29 (19). Large species, about 6 mm. long; color ash gray with triangular 
spots on pronotum; body covered with hluish-w hite bloom. 
On various hosts; common on hickory and sycamore 
Longistiqma (p. 127). 
Smaller species, usually 5 mm. or less in length. 
See appropriate host. 
Alder: Causing mottling or dropping of leaves. Insects 1% to 2 
mm. long; color ereen or greenish yellow, abdomen uniformly 
colored or dusky spotted Penne ead eS Myzocallis (p. 129). 
On underside of leaves or on stems. Insects 2 to 4 mm. 
long; color brownish, covered with white floeculence 
Proctphilus (p. 182). 
Beech: On underside of leaves. Insects 2 to 3 mm. long; color 
bluish white to greenish yellow, covered with white floceu- 
1V:) 06. eC Seca tae om SOURS CON ERI Meh on Se Phyllaphis (p. 129). 
On underside of branches or on trunk. Insects 2 to 4 mm. 
long; color brownish, covered with white floeculence 
Prociphilus (p. 132). 
