Bronze Birch Borer Description:

The bronze birch borer (Agrilus anxius) is a destructive beetle that feeds on birch trees. Signs of this pest include off-color and sparse foliage in the upper canopy of the birch tree, dead branches in the upper crown, and swollen ridges on the trunk and branches. Small, D-shaped holes in the bark are the exit points of the adult beetle.


This borer feeds on birch trees weakened from drought, poor growing conditions, or other insect infestations, such as birch leafminer. European birch, Betula pendula, is highly prone to borer attack. The native paper birch (Betula papyrifera) is less susceptible, but not immune.

Biology & Symptoms:

Borer larvae make long, winding tunnels under the bark. This disrupts the vascular tissues, causing the trunk or branch to die from a lack of water and nutrients.

Bronze Birch Borer Treatment & Management:

Applications in early to mid-spring can reduce further borer infestations. Applications need to be made on rough areas of the bark on the main trunk and limbs, and especially at branch-trunk ridges. However, do not expect to control larvae that are already inside the tree. A recent treatment involves using a soil-injected product in late summer/fall or early spring to reduce borer damage during the next growing season. When considering planting a birch tree, select well-drained, sandy, or loamy soil. Birches struggle in clay soils. Keep the tree healthy by proper fertilizing, watering, mulching, and managing other insects and diseases. Fertilizing can increase a birch’s tolerance to borer attack and help it overcome previous borer damage. Plant more tolerant species such as native paperbark, Betula papyrifera.

See More Articles

Pest And Disease Chlorosis Banner 1440X500
Leaf or Needle Discoloration


Chlorosis is the result of a lack of chlorophyll production that may be caused by many conditions such as another disease, soil/water pH or nutritional imbalance, or tree wounds.
Read More
Pest And Disease Borers Banner 1440X500
Trunk or Bark Damage

Tree Borers

Borers are chewing insects, usually in larval stages, that chew and feed on the inner bark and/or wood of trees. Most species are the larvae of beetles.
Read More
DSC 8019
DSC 8019

Get In Touch With Us!

We pride ourselves at Davey Tree on providing prompt, professional and personalized service from certified arborists that live, work and engage in your community. Contact one of our Davey Tree specialists for your residential needs.

Let's Find What
You're Looking For!