Poplar and willow borer
Last updated on January 30, 2025Crytorhynchus lapathi
Introduced to North America from Europe, poplar and willow borer infestations in British Columbia are most common on Vancouver Island and in southern interior valleys.
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Description
The lifecycle of the willow borer can be as long as three years. Females deposit eggs in deep holes chewed in the bark. The larvae bore through the inner bark and then into the wood and excavate extensive tunnels. Larvae cause the most damage while attacking trees ranging in diameter from 2cm to 8cm. The feeding can result in stem breakage, irregular splits and holes in the bark.
Adults also cause damage by feeding on branches and the main stem with a preference for young succulent bark. While most common on Vancouver Island and interior valleys, the borer can be found in most river drainages and along highway corridors from the coast to the central interior.
Host tree species
Willows are the primary host but the borer also attacks various species of poplar including black cottonwood, balsam poplar and hybrid poplars.
Damage symptoms.
Upper crowns or whole trees can be broken over or dead due to stem weakness caused by larval tunneling. Splits and holes in the bark are accompanied by piles of white shavings around the stem.
Further reading
Read more about the willow and poplar borer in the Field Guide to Forest Damage in B.C. (PDF, 6.5MB)