Although small in size, the White Pine Weevil can cause a lot of damage to spruce and pine trees. 

The weevil does not kill the tree, but it causes the tree to loose its shape. The damage is caused by the larvae which feed under the bark of the tree’s leader (top of the tree) . As the larvae feed in the stem, they cut off the needed water and nutrients thus causing the leader to curl, drop its needles, turn brown and die. The larvae only attack the tree’s leader leaving the rest of the tree untouched.

Spruce trees that are affected by White Pine weevil do not grow taller and loose their pyramidal shape making them less attractive.

Over the spring/summer the white pine weevil have been active in the Prince George area, including my yard. We have spruce trees growing in our yard and over the past few years the trees have been attacked by the weevil. The weevil can be controlled but there is a very short time frame, and if you miss spraying them with a pesticide you will end up loosing the trees leader. If you had the problem this past summer you will more than likely have it again next season.

In early spring as soon as the snow melts the adult weevils wake up from their dormant state and climb (or sometimes fly) up the tree to feed, breed and lay their eggs at the base of the leader. This is the time to use a pesticide when the adults are active.

The top of the tree is sprayed with Malathion, following the manufacturer’s directions on the container. If the adult weevil is not destroyed, the female will lay her eggs and when the eggs hatch the larvae will bore into the stem and feed. If this happens, and you begin to see the top of the tree (leader) curl, and brown, remove the leader as quickly as possible and destroy it. This is the mechanical way of getting rid of the weevil. Cut the affected stem back to the healthy growth just above the whorl of unaffected branches. Do this before the adults emerge from the stem in late summer.

If there are small emergence holes in the stem the adults have evacuated the stem. The adults will continue to stay and feed on the tree until fall when the weather becomes cold and then they go down to the bottom of the tree and overwinter. An adult weevil can live for several years.

A spruce tree that lost its shape can have it back again with some pruning and staking the strongest lateral branch upwards. When a tree reaches heights of 20 feet or more they are rarely bothered by White pine weevil, or if they are in a shaded area. It seems that White pine weevils prefer trees that receive lots of sun.

-Jos

Jos Van Hage owns and operates two Art Knapp Home and Garden Centres in Prince George:

• Highway 16 west at Kimball Road

• Highway 97 North at Northwood Pulpmill Road ( closed for the season)