Western hemlock looper

Lambdina fiscellaria lugubrosa (Hulst) (Lepidoptera: Geometridae)

Orientation to pest

Western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), is a native North American geometrid whose larvae defoliate western hemlock (Tsuga heterophylla [Raf.] Sarg.) in coastal areas of Oregon, Washington, and British Columbia. Adults fly in late summer or fall and lay eggs on bark, or associated moss and lichens or even downed logs. Winter is spent in the egg stage and larvae begin to feed in the late spring. Young larvae may feed on understory vegetation of various kinds of trees or shrubs. Initial feeding on hemlock is concentrated in the buds. In summer, older larvae attack old needles, some of which are notched but not severed. These remain attached, giving the tree a brown appearance. Mature larvae spin silk threads and drop to the ground to pupate in the late summer. New moths emerge in fall to lay overwintering eggs. Repeated large outbreaks occurred over wide areas in western North America in the past, damaging large volumes of old growth hemlock. However, since old growth hemlock stands in many areas have been logged, outbreaks have become smaller.

Hosts commonly attacked

This moth feeds mainly on western hemlock (T. heterophylla), but during outbreaks other conifer species and hardwood shrubs are also attacked.

Distribution

This geometrid is found in western North America in coastal forests of Oregon, Washington, and British Columbia.

Images of western hemlock looper

Jerald E. Dewey, USDA Forest Service, Bugwood.org 768x512 / 1536x1024	Jerald E. Dewey, USDA Forest Service, Bugwood.org 768x512 / 1536x1024	Bruce Hostetler, USDA Forest Service, Bugwood.org 768x512 / 1536x1024	USDA Forest Service - Ogden Archive, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Figure 1. Adult of western hemlock looper, Lambdina fiscellaria lugubrosa	Figure 2. Larva of western hemlock looper	Figure 3. Defoliation of a western hemlock stand by western hemlock looper	Figure 4. Defoliation of a western hemlock stand by western hemlock looper

Important biological control agents related to this pest species

Pupal parasitoids reported from this species in Alaska included eight ichnuemonids: Pimpla pedalis Cresson, Pimpla aquilonia Cresson, Pimpla hesperus (Townes), Apechthis ontario (Cresson), Itoplectis quadricingulatus (Prov.), Masttus laplantei Mason, Cratichneumon sp. (probably C. ashmeadi [Schulz]), and Aoplus velox occidentalis (Harrington).

Web links for information on western hemlock looper

• Fact Sheet | Natural Resources Canada
  
• Management Guide | FHP and State Forestry Organizations

Articles

• Torgersen, T. R. 1971. Parasites of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), in southeast Alaska (Lepidoptera: Geometridae). Pan-Pacific Entomologist 47:215-219.
• Harris, J. W. E., A. F. Dawson, and R. G. Brown. 1982. The western hemlock looper in British Columbia 1911-1980. Report BC-X-234, Pacific Forest Research Centre, Canada. 18 pp.
• Mills, N. J. and M. Räther. 1990. Hemlock loopers in Canada; biology, pest status and potential for biological control. Biocontrol News and Information 11(3): 209-222.