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White pine weevil
Pissodes strobi (Peck)

This native North American forest insect is the most prevalent conifer pest occurring throughout the range of eastern white pine. White pine is the most common host, but all pines and spruces may be attacked. In British Columbia, this insect occurs throughout the range of spruce except for the Queen Charlotte Islands. Its preferred hosts are Sitka, white, and Engelmann spruce.

Both the larvae and adults damage trees by feeding because they attack the terminal shoot (leader) of the tree. Although the small puncture holes in the bark caused by adults are not serious themselves, these holes increase the risk for fungal pathogens to enter. The larval feeding in the inner bark causes the most damage by severely affecting the conducting tissues. Although shoots from the previous year are attacked, the effect is first seen in the current year's shoots as they droop and turn reddish brown. This type of feeding affects 2 years of growth and repeated attacks could kill the tree. More importantly, the deformities and growth reduction caused by the white pine weevil affect the commercial and aesthetic quality of the tree.

Points of interest

• one generation per year and overwinters in the adult stage
• first found in 1817 in North America and not until this century has it been considered a serious threat to forest resources
• in plantations, growing white pine and spruce under a canopy of broad leaf trees can reduce weevil injury
• particularly harmful in Ontario, attacks have been reported every year since the 1930s
• in British Columbia, this pest was previously called Sitka spruce or Englemann spruce weevil
• average of mature larval or full-grown length is 4–10 mm

References

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.

Martineau, R. 1984. Insects Harmful to Forest Trees. Multiscience Publications Ltd., Montreal, Environment Canada, Canadian Forestry Service, Ottawa, and Supply and Services Canada, Canadian Government Publishing Centre, Ottawa. For. Tech. Rep. 32. 261 p. + x.

Rose, A.H.; Lindquist, O.H.; Nystrom, K.L.> 1999. Insects of Eastern Pines. Natural Resources Canada, Canadian Forest Service, Ottawa. Revised edition. Publ. 1313. 128 p.