Pissodes strobi (Curculionidae)

The Sitka spruce weevil (white pine weevil)

Adults:

Reddish brown with patches of lighter brown or grey scales. Note moderately slender snout and slender form. 4-5 mm long.

Larvae:

Curved legless grubs, yellowish white with light brown heads and smooth-surfaced.

Damage:

Adults lay eggs in punctures which they chew in the bark of the year-old leader during April and May. Larvae feed colonially beneath the bark, working downwards and destroying phloem as they go. Consequent wilting or suppression of new leader results in the axis of the tree becoming deformed, forked or bushy.

Principal Hosts:

Sitka, Englemann and white spruces in B.C., eastern white pine.

Economic Importance:

Heavy attack on previous year's leader can result in the loss of 3 or 4 years of height growth. Laterals then compete for dominance and this can result in forking or heavy branching. The resulting bushy, heavy branched poles have very little value as compared to straight stemmed mature trees. This is a very important pest in B.C. and it effects on stands are so devastating that Sitka spruce is no longer planted in pure stands.

References and Links:

EAG: 556-558; FC: 332.

See HForest for the PFC pest leaflet, and JP17.

Also, see the White Pine Weevil Homepage, by Dr. Rene Alfaro of the Pacific Forestry Centre and Dr. Robert Lavallee of the Laurentian Forestry Centre. Hypertext links enable the reader to review the weevil's life cycle, symptoms of weevil attack, damage caused by weevil attacks and management options for Pissodes strobi.

And, see the BC Forest Practices Code Terminal Weevils Guidebook (1996), which describes the life history, impact, survey methods, and management options of the terminal weevils, Pissodes strobi, the spruce weevil and Pissodes terminalis, the lodgepole terminal weevil, in young stands in BC.

Additional Images: