Forest pest identification

Forest damage is caused by insects, diseases, animals and abiotic agents. To determine whether damage is serious or manageable, identify the damaging agent.

Online resources for damage agent identification 

• Field Guide to Forest Damage in B.C. (PDF, 6.5MB)
• Common Tree Diseases in British Columbia
• Diseases and Insects in B.C. Forest Seedling Nurseries (PDF, 22MB)
• Bugwood Image Database
• USDA Forest Service Pacific Northwest Region – Forest and Grassland Health
• Jim Worral’s Forest Pathology course

Signs to look for

To identify the damaging agent, you must 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 and 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
• Unusual swellings on stems
• Spores and fruiting bodies (mushrooms)
• Cankers
• Dead or dying leaders or branch tips
• Shepherd's crooks

Also examine the base of the tree to determine if it has been damaged due to construction, flooding or drought.