112 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
FIELD KEY TO THE APHIDS, BASED PRINCIPALLY ON HOST PLANTS—Continued 
29 (19). Large species, ete—Continued 
aa. Color not brownish; either yellowish, reddish, 
or shading to green—Continued 
d. Four alternatives—Continued 
On Norway and sugar maple, on underside of 
leaves; 2 to 24% mm. long; color yellowish 
green marked with brown on thorax and 
abdomen, or with head, antennae, thoracic 
lobes, sternal plates, and cornicles black or 
vellowish to apple green; antennae rather 
yi eee eee ee eo OAS, (Gay, 3). 
On Norway, sycamore, or English maple, on 
underside of leaves; 2% to 3 mm. long; color 
yellow or reddish to green, with black mark- 
ings or bands, legs and cornicles yellow to 
dark oranges = =e Drepanosiphum (p. 129). 
On underside of leaves; 2% mm. long; color 
olive green or pale sordid green 
Drepanaphis (p. 129). 
Oak (three alternatives): 
Causing mottling or dropping of leaves; 144 to 2 mm. long; 
color green or greenish yellow, abdomen uniformly colored 
Onrispottediduskay ss ee oe Myzocallis (p. 129). 
On leaves; 144 to 2 mm. long; color pale vellow; costal vein 
yellow or brown or brown band extending beyond stigma, 
antennae ringed with brown_______-_--___- Monellia (p. 129). 
On underside of leaves; 2 to 3 mm. long; color yellow, 
antennae uniformly yellow or ringed with brown 
Therioaphis (p. 129). 
Poplar (three alternatives): 
On sprouts or tender growth; 2 to 24% mm. long; color yellow- 
ish or greenish, with brown mottling, head brown 
Neothomasia (p. 129). 
On leaves and twigs; 3 to 4 mm. long; color dusky reddish to 
dark yellowishvereen a= ess. 2: eee Clavigerus (p. 129). 
On leaves and twigs; about 5 mm. long; color ash gray due to 
white pruinosity over base color of brown, abdomen 
marked with black spots; large black tubercle on 4th 
abdominal\seome nt sate ab eee een ane _Lachnus (p. 127). 
Sycamore: Length about 6 mm.; body covered with bluish- 
Wi FeSpPLULMOST tyes see eel eee ene _Longistigma (p. 127). 
Length 2 to 4 mm.; covered with white flocculence 
Prociphilus (p. 132). 
Walnut: On leaves; 1% to 2 mm. long; color pale yellow or 
brown, or brown band extending beyond stigma; antennae 
Tin ged ewathe brows = aoe ee alee olen neler Monellia (p. 129). 
Willow: Length 3 to 4 mm.; color dusky reddish to dark 
vellowishveneentiss=s ons Saas Clavigerus (p. 129). 
Length about 5 mm.; color ash gray due to pruinosity over 
base color of brown, abdomen marked with dark spots 
Lachnus (p. 127). 
SuporperR HETEROPTERA 
The suborder Heteroptera comprises a group of sucking insects, 
some of which are aquatic or subaquatic, while others are terrestrial. 
They range in size from certain tropical species of the family Belos- 
tomatidae, which attain a length of 3 to 4 inches, to species of Micro- 
physidae and Cryptostemmatidae, which may be less than a millimeter 
Jong. Of the fifty-odd known families of this suborder, only 9 or 10 
are of much importance and most of these do little actual damage to 
forest growth. 
