Spruce (Picea)-White pine weevil

Pissodes strobi

Pest description and damage White pine weevils are brown beetles with light blotches on the highly curved back. Adults grow to about 0.25 inch long and feed on shoots and needles of pine and spruce. The larvae feed on needles and also mine shoot tips, often distorting or killing back the terminals and causing trees to appear deformed. Infested terminals often develop a "shepherd's crook" appearance. The weevil attacks eastern white pine (Pinus strobus), Sitka spruce (Picea sitchensis), and a wide variety of other pines and spruce and even Douglas-fir.

Biology and life history Adult beetles overwinter in litter on the ground. In the spring, adults walk or fly to host trees, where they settle on the leader to mate. Eggs are deposited in a cavity on the tree. The eggs hatch, and the larvae commence feeding in the bark, killing the leader. As they feed, the current season's growth is emerging, but this soon collapses, causing the characteristic "shepherd's crook." The larvae then bore into the wood to pupate. The adult beetles emerge in late summer (around mid-August into fall) and overwinter in organic debris on the ground.

Management-cultural control

Prune and destroy affected terminals in the summer before adult beetles emerge. This will help reduce next year's infestation.

Management-chemical control

See Table 2 in:

For more information

Hamid, Abdul, T.M. ODell, and S. Katovich. 1997. White pine weevil. Forest Insect and Disease Leaflet 21. USFS.

Rosetta, R. 2007. White pine weevil (http://oregonstate.edu/dept/nurspest/white_pine_weevil.htm)