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By L. S. Unger
Spruce budworms, Choristoneura species (Lepidoptera: Tortricidae), are destructive defoliators of conifers. The first recorded outbreak in British Columbia was in 1909, and since then infestations have occurred in all forest regions.
Severe defoliation results in reduced increment, deformity, dieback, mortality of regeneration, and some mortality of merchantable trees. Additional trees may be killed by sec-ondary pests such as bark beetles dur-ing and following infestations due to the predisposition of defoliated trees.
Four species of Choristoneura are important in British Columbia: C. occi-dentalis Freeman (western spruce bud-worm, or western budworm), C. biennis Freeman (2-year-cycle budworm), C. fumiferana (Clemens) (spruce bud-worm), and C. orae Freeman.
For more information, see the Spruce budworms Forest Pest Leaflet in the Canadian Forest Service bookstore.