of branches; older ones devour all but the midribs or larger veins of the leaves. They 
become mature in 5 to 6 weeks at which time they drop to the ground and enter the 
soil where they pupate in tough cocoons made from silk and soil particles. Adults 
emerge from November to January and in some localities into the springtime, 
usually following some freezing weather. Reproduction is by sexual mating and a 
type of parthenogenesis tentatively described as gynogenesis (the genotypes are 
only of the female) (866, 1067). Females climb the trees, mate, and deposit about 
100 brownish eggs in compact, uniform rows of single layers on the trunk, smaller 
twigs, and branches (397). There is one generation per year. 
The fall cankerworm is an important pest of forest and shade trees. Outbreaks 
occur periodically and sometimes cover large, forested areas. Shade trees in urban 
areas are subject to heavy infestation and may be seriously damaged. Severe 
infestations in recreational areas are particularly annoying. Natural control by the 
egg parasite, Telenomus alsophilae Viereck, 1s a major factor in the decline of fall 
cankerworm populations (398). 
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, quaking aspen, willow, and beech, but many other 
hardwoods such as paper birch, red oak, pin cherry, common chokecherry, alder, 
and serviceberry are also attacked. Serious outbreaks have occurred in both the 
United States and Canada. 
Female moths are light brownish-gray and practically wingless. Males are light 
brown and have fully developed wings; their forewings are semitransparent, banded 
with brown or gray, and have a wingspread of 25 to 30 mm. Full-grown larvae may 
vary from bright green to dark brown and have three narrow yellow stripes on each 
side; larvae are about 18 mm long. 
In Canada, 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 thin, silk cocoons in the soil or 
duff. Adults appear in the fall. The female climbs trees and deposits eggs singly in 
bark crevices, under loose bark, or in other sheltered locations on the tree (/62). A 
polyhedrosis virus disease has occurred commonly in New Brunswick infestations. 
The winter moth, O. brumata (L.), an introduced species known to have been 
present in Nova Scotia since about 1930, now occurs also on Cape Breton and 
Prince Edward Islands, and in the Pacific Northwest. Although it was originally 
found in the United States at Portland, Oreg., in 1958, the male specimens were 
previously misidentified and not correctly determined until 1978. The female moth 
has a dusky-brown to silver-gray body with occasional irregular black spots and is 
practically wingless. Males have fully developed wings with a wingspread of 27 to 
30 mm. The body is dusky brown with black spots and the forewings are dusky 
brown with obscure markings. 
The most common hosts are apple, northern red oak, American elm, red maple, 
basswood, and eastern hophornbeam, but a number of other hardwoods are also 
attacked, such as poplar and willow. Persistent severe attacks result in thin tops, 
dead twigs and branches, and ultimately the death of trees. Severe defoliation of 
principal host trees often occurs in Nova Scotia. 
Winter is spent in the egg stage and hatching occurs from late April to late May. 
Young larvae feed first on opening buds and on the undersides of developing leaves. 
Older larvae feed inside loose leaf rolls. When larvae become mature, they drop and 
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