An insect that can kill birch trees

Bronze Birch Borer is a native beetle that attacks birch trees throughout North America. In urban landscapes it is primarily a pest of white-barked birch trees that are planted in stressed environments or that have no resistance to the beetles (Asian and European birches). This pest will kill untreated trees that become infested.

Infested Birch trees require treatment for control
All white barked birch species are susceptible to the Bronze Birch Borer and require a systemic insecticide treatment for control.
Treatment timelines will vary and are dependent upon the levels of tree infestation.

What to look for
• D-shaped holes in the bark showing where adult borers have exited.
• Ridges on the bark of larger branches and tree trunk.
• Dieback from the top down.

Life Cycle
• Full-size larvae develop through the winter in the bark (overwinter).
• Adult beetles emerge in late spring.
• Beetles feed on leaves and mate shortly after emergence.
• Female beetles lay eggs in bark cracks and crevices.
• Larvae emerge, chew through bark, and enter the living tissue.
• Larvae feed and move through the living tissue and disrupt water, and sap flow.

Treatment and Prevention
• Do not fertilize without increasing water availability.
• Plant trees in clumps so that the root system has shade from other trees or structures.
• Water trees during drought periods. Drought conditions exist when less than 1 – 1½” of rain has fallen per week.
• Mulch tree or treat with Forest Floor Service.

Treatment timelines are dependent upon your tree, landscape, insect infestation levels, time of season, and available treatment options.

Dieback starts from the top of the birch and moves downward.
Bronze Birch Borer damage.
Relative size of adult borer and its larvae.