Fir (Abies)-Spruce budworm

Pest description and crop damage Adult moths are mottled orange-brown and have a wingspan up to 1 inch. The larvae are typically green to brown with a darker head and grow to approximately 1 inch in length. These larvae feed on the buds and foliage and may tie shoot tips together with webbing to make a nest.

Spruce budworms are mainly pests of balsam and subalpine firs. They also attack spruce and Douglas-fir. Although a significant problem in forestry situations, this insect is an infrequent pest in the landscape.

Biology and life cycle The larvae overwinter in small silken cocoons which are hard to locate. The following spring, larvae emerge and spin long silken threads that aid in their dispersal. Eggs are light green and laid in shingle-like masses on the underside of needles in mid-July.

Management-biological control


Management-cultural control

Hand-pick larvae when found.

Management-chemical control


Apply in May and again in June.

See also "True firs" in:

For more information

Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 28).