WEB July 2010
By
Lee Pederson
US Forest Service
Forest Health Protection and State Forestry Organizations
| Management Guide For White Pine Weevil |
| Pissodes strobi(Peck) |
| This is the most significant pest of spruce reproduction in the Northern Region. | Host:
|
Damage It attacks and kills or badly injures terminal leaders on spruce reproduction from 1 to 30 feet in height. This may result in dieback, height growth loss, or deformity of the main stem. Repeated attacks can produce multiple leaders, and may also result in tree mortality. White pine weevil damage on the main leader. Photo by William Ciesla
Key Points
Damage is dieback, height growth loss, or deformity of main stem.
Only one generation a year.
Newly hatched larvae feed down the terminal just under the bark.
Life History There is only one generation a year, but brood development overlaps. Most stages can be found at any time from spring to fall, and all stages except the egg can overwinter. They typically overwinter as adults in debris on the forest floor. Adults emerge and make feeding punctures (resin droplets are usually associated with these wounds) in the bark of the previous year’s leader in May, and by June females lay eggs in the punctures. Newly hatched larvae feed down the terminal just under
the bark and become mature about midsummer. During that time, the current year’s leader will distort and wilt to form a “shepherd’s crook”. This gradually fades to yellow, red, and then gray or brown, which indicates weevil attack. Oval-shaped pupal cells are constructed in the wood and covered with shredded wood fiber (chip cocoons). Emergence of new adults continues from August until fall. They feed at random on bark and then drop to the ground to overwinter.
