States and Canada. Its body is usually yellowish-green with 
brownish marks on the thorax and abdomen. Walks, benches, or 
cars parked beneath infested trees are often badly soiled. The 
related species, the Norway-maple aphid, P. lyropictus (Kessler), 
often completely defoliates Norway and sugar maple trees. Honey- 
dew dripping from infested leaves is a nuisance. P. americanus 
(Baker), Drepanaphis acerifoliae (Thomas), D. carolinensis 
Smith, D. nigricans Smith, D. sabrinae Miller, and Drepanosi- 
phum platanoides (Schrank) are also found on maples. 
Numerous species of Myzocallis such as M. bella (Walsh), M. 
alhambra Davidson, M. discolor (Fitch), and M. melanocera 
Boudreaux and Tissot feed on various oaks. Other common mem- 
bers of the genus and their hosts include M. alnifoliae (Fitch) — 
alder; M. tiliae (L.)—native and introduced lindens; the crape- 
myrile aphid, M. kahawaluokalani Kirkaldy—crapemyrtle; the 
black pecan aphid, M. caryaefoliae (Davis)—hickory and pecan; 
and the elm leaf aphid, M. ulmifolii (Mon.)—elm. 
Many other species of free-living aphids also occur commonly 
on various deciduous trees. These include Monellia caryella 
(Fitch), M. costalis (Fitch), M. microsetosa Richards and Movnel- 
liopsis nigropunctata (Granovsky)—hickories; Chaitophorus ste- 
vensis Sanborn, C. populicola (Thomas) and Pterocomma populi- 
foliae (Fitch)—poplars; P. smithae (Monell)—poplars and 
willows; P. salicis (L.)—willow; Macrosiphum lirtodendri (Mo- 
nell) —yellow-poplar; Aphis craccivora Koch—black locust seed- 
lings; Calaphis betulaecolens (Fitech)—birch (often in large 
numbers); C. betulella (Walsh)—bireh and beech; Huceraphis 
betulae (Koch)—various birches, especially yellow birch; LF. 
lineata Baker—gray birch; and E. mucidas (Fitch)—river birch. 
Three species of woolly aphids are commonly found on elms in 
Eastern United States. The woolly apple aphid, Hriosoma lani- 
gerum (Hausm.), feeds on new terminal leaves, causing them 
to curl or appear in the form of rosettes (It also attacks 
apple, pear, hawthorn, and mountain-ash. Damage to elm is not 
especially severe.). The presence of large numbers of distorted 
leaves on shade trees is unsightly. The woolly elm aphid, FE’. ameri- 
canum (Riley) has elm as a primary host and shadbush as an 
alternate host. It feeds at the edges of young elm leaves in the 
spring, causing them to swell, curl, and roll inward from the edge. 
Two generations are produced on elm. Then, members of the 
second generation fly to shadbush and attack its roots. The 
Summer is spent here. During the fall, a winged generation de- 
velops which flies back to elm where it lays a crop of over- 
wintering eggs. #. rileyi Thomas, the woolly elm bark aphid, at- 
tacks American and slippery elm. It occurs in dense woolly 
clusters on the limbs and trunks, causing knotty growths to form 
at the sites of injury. Heavily infested trees may be seriously 
injured. Hawthorn is infested by the closely related species, EF. 
crataegi (Oest.). It occurs in dense colonies on twigs and branches 
and is occasionally injurious to ornamentals. 
Several other woolly aphids are also found on various species of 
hardwoods. The beech blight aphid, Prociphilus imbricator (Fitch) 
feeds on the trunk and undersides of leaves and branches of beech 
from New England to Georgia and Illinois. Its body is covered 
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