Forest insects
Last updated on January 30, 2025Both non-invasive and invasive insects damage forest health in British Columbia. These pests can cause extreme damage to the forest and require management strategies to both minimize the damage and recover from the effects.
Signs of insect damage
To identify the damage agent, observe and describe the signs and symptoms on the host tree. Try to observe the organism damaging the tree, but also look for:
- Signs of feeding (chewing marks, frass, shavings, defoliation)
- Pitch tubes or entrance/exit holes on the trunk
- Larval galleries or fungi under the bark
- Webbing and partially eaten needles
- Dead tops
- Yellowing or discoloured foliage
- Crown thinning
- Distress cone crops
- Decay
- Dead or dying leaders or branch tips
- Shepherd's crooks
Several of the damage symptoms listed above can be caused by other factors. Examine the base of the tree to determine if it has been damaged due to construction, flooding or drought.
Damage agents
Bark beetles
Bark beetles are small, cylindrical insects that can attack and kill trees by boring through the bark and mining the phloem (the layer between the bark and wood) of a tree.
Weevils
Weevils are a group of insects related to beetles that are distinguished by their long noses. They can harm tree volume and wood quality by causing stem deformation and height loss
Defoliators
Defoliating insects feed on the leaves or needles from trees. Depending on the duration and the severity of defoliation, tree growth may be stunted. Top-kill and eventual tree mortality can result.
Reporting insects in B.C.
Watch for and report invasive and migratory pests that harm plants and cause damage to Canada's environment, farm land, forests, parks and other natural areas. Early detection is critical for slowing the spread of insect pests. Learn more about priority insect pests to watch out for and use the QR code in the poster link below to report your detection. This initiative is a collaborative project developed by the Insect Surveillance Community of Practice of the Canadian Plant Health Council, a multi-partner body that coordinates action for the protection of plant health in Canada.
Contact information
Contact us if you have further questions about Forest Health in B.C.