Western hemlock looper
- French common name: Arpenteuse de la pruche de l'Ouest
- Scientific name: Lambdina fiscellaria lugubrosa (Hulst)
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Lepidoptera
- Family: Geometridae
Distribution
British Columbia
Damage, symptoms and biology
Hemlock looper damage usually occurs in mature stands where severe defoliation can result in growth reduction, top-kill and tree mortality.
This species overwinters as eggs laid on moss, lichens or bark. Eggs hatch from May to early June. The young larvae initially feed on the new foliage but as the larvae mature they feed on foliage of all ages. The larvae are wasteful feeders and leave behind partially consumed needles. Larvae are present from June to early September. Pupation occurs on foliage, or on tree trunks or in the duff from late July to early September. After a 10- to 14 day pupation, adults emerge and are in flight from September to October.
Mature larva to 30 mm long. Head, brown with eight prominent black spots. Body light to dark grey, complex pattern of alternating grey to cream-coloured longitudinal lines; four prominent dark spots on the dorsum of each abdominal segment.
Other information
The western hemlock looper is one of the most destructive forest defoliators in British Columbia. Major outbreaks have occurred on the coast (on Vancouver Island and adjacent south coast in 1945-46) and in the interior wetbelt (upper Fraser River 1954-55, 1991-92; North Thompson-Wells Gray Park 1976 and 1991-92; Arrow Lakes 1972-73; Shuswap Lake 1983-84; Horsefly Lake-Quesnel Lake 1946, 1984 and 1991-92; and Revelstoke 1945-47, 1972-73, 1982-83 and 1991-93).
During outbreaks, this looper will also feed on understory shrubs.
Canadian Forest Service Publications
Information on host(s)
Main host(s)
Amabilis fir, Engelmann spruce, grand fir, Rocky Mountain Douglas-fir, Sitka spruce, subalpine fir, western hemlock, western larch, western redcedar, white spruce
Photos
Lateral view of mature larva on western hemlock.
Robert W. Duncan Centre de foresterie du Pacifique, Victoria (Colombie-Britannique) / Pacific Forestry Centre, Victoria, British Columbia