back. Green larvae have longitudinal white lines. There are three 
pairs of prolegs—a very small vestigial pair on the fifth ab. 
dominal segment and larger pairs on the sixth and anal segments. 
The fall cankerworm spends the winter in the egg stage, and 
hatching occurs in late April or early May. Young larvae skele- 
tonize the young leaves at the tips of branches; older ones devour 
all but the midribs or larger veins of the leaves. They become 
mature in 5 to 6 weeks and drop to and enter the soil where 
they make cocoons in which to pupate. Adults emerge in Novem- 
ber or December, usually following some freezing weather. Fe- 
males climb the trees and deposit about 100 eggs in compact, 
uniform rows of single layers on the smaller twigs and branches. 
There is one generation per year. 
The fall cankerworm is an important pest of forest and shade 
trees. Outbreaks occur periodically, sometimes covering large, 
forested areas. Shade trees in urban areas are subject to heavy 
infestation and may be seriously damaged. Heavy infestations 
in recreational areas are particularly annoying. 
Synchlora aerata (F.) feeds on the foliage of willow and apple 
in New York State. Full-grown larvae are brownish, have curved 
appendages on the dorsum, and are about 20 mm. long. Winter 
is spent in the pupal stage, and there may be two generations 
per year. 
The Bruce spanworm, Operophtera bruceata (Hulst), occurs from 
coast to coast in Canada and from New England to the Lake 
States. In eastern America its preferred hosts are sugar maple, 
trembling aspen, willow, and beech, but many other hardwoods 
such as white birch, red oak, pin and choke cherries, alder, and 
shadbush are also attacked. Serious outbreaks have occurred in 
both the United States and Canada. 
Female moths are light brownish-gray in color and practically 
wingless; males are light brown and have fully-developed wings. 
The forewings are semi-transparent, banded with brown or gray, 
and have an expanse of 25 to 30 mm. Full-grown larvae are bright 
green except for three narrow yellow stripes on each side; larvae 
are about 18 mm. long. 
In Canada, the winter is spent in the egg stage and hatching 
occurs in early spring. The larvae feed either openly on leaves 
or within the shelter of leaves loosely rolled and webbed together 
with silk. In heavily infested stands, trees are sometimes literally 
festooned with this silk. Pupation occurs in cocoons in the soil 
or duff. Adults appear in the fall. The female climbs trees and 
deposits eggs in bark crevices, under loose bark, or in other hid- 
ing places on the tree (111). A polyhedrosis virus disease has 
occurred commonly in New Brunswick infestations. 
The winter moth, Operophtera brumata (L.), an introduced spe- 
cies known to have been present in Nova Scotia since about 1930, 
now occurs also on Cape Breton and Prince Edward Islands and 
in New Brunswick. So far, it is not known to occur in the United 
States. If it continues its recent rate of spread, however, it may 
soon cross the border. The female moth has a dusky brown to 
silver gray body with occasional irregular black spots and is prac- 
tically wingless. Males have fully developed wings with an ex- 
panse of 27 to 30 mm. The body is dusky brown with black spots 
336 
