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Western blackheaded budworm
Acleris gloverana (Wlshm.)

Native to North America, this defoliating insect occurs throughout British Columbia, except for the Ponderosa Pine Biogeoclimatic Zone. Its principal hosts on the coast are western hemlock, amabilis fir, and Sitka spruce. In the Interior, western hemlock, Engelmann spruce, white spruce, subalpine fir, and Douglas-fir are attacked. During epidemics, this species may also occur on other coniferous species. Like its eastern counterpart, it is considered of major importance due to its potential to kill or severely damage trees during an infestation. Generally, the larvae, preferring the upper crown, feed on new needles only partially eating the buds. Severe defoliation can lead to growth reduction and an increased possibility for secondary attack by other pests. During an epidemic the larvae will attack old needles and can completely defoliate the tree. Successive years of defoliation can kill the tree.

Points of interest

• damaged stands have a reddish brown hue because of the dead needles caught in silk strands
• average of mature larval or full-grown length is 15 mm

References

Koot, H.P. 1992. Western blackheaded budworm. Forestry Canada, Pacific Forest Centre, Victoria, B.C. Forest Pest Leaflet 24. Revised. 4 p.

Finck, K.E; Humphreys, P.; Hawkins, G.V. 1989. Field Guide to Pests of Managed Forests in British Columbia. Forestry Canada, Victoria, B.C., and B.C. Ministry of Forests, Victoria, B.C. FRDA Joint Report No. 16. ISBN 0-662-17153-5. 188 p. + viii.