Bronze Birch Borer: Symptoms and Treatment

As the number-one provider of residential tree care and inspection services in various areas of Pennsylvania, our licensed arborists at Rick’s PHC Certified Arborists notice bronze birch borer symptoms in many trees in suburban and commercial settings.

Numerous clients call us wondering why European white birch trees are shedding leaves and experiencing branch dieback. Because birch trees encompass a broad range of cultivars and subspecies, landscapers and residents view them as desirable landscape specimens. However, they experience higher stress levels in suburban and commercial environments without professional care. Poor cultural practices and site selection leave them vulnerable to insects like the birch borer (Agrilus Anxius) and the birch sawfly (Cimbex Femoratus), which can cause tree death when left unattended.

What bronze birch borer symptoms should you watch out for, and can you save a heavily infested tree? Our licensed arborists will answer your birch pest-related questions in this article.

What Is the Bronze Birch Borer?

The bronze birch borer is one of the most well-studied and documented threats to birch trees in Canada and the United States. Throughout the 20s and early 30s, arborists thought they only resided in stressed and dying woodlands, living off dead and decaying tissues of birch trees. Today, you can find them in virtually every suburban and commercial setting.

Birch species have varying levels of vulnerability to the bronze birch borer. For example:

• The whitebarked Himalayan birch, or Betula jacquemontii, is the most vulnerable type for infestations.
• The European white birch and subspecies of the Betula pendula are highly susceptible.
• The cherry birch and its subspecies are less likely to host the bronze birch borer.
• The heritage river birch and other Betula nigra subspecies are nearly immune to infestations.

Bronze Birch Borer Symptoms

Bronze birch borer symptoms of infestation include:

• Sawdust-packed tunnels beneath the hardened bark tissue of European white and whitebarked Himalayan birch trees
• Bumps and ridges on birch branches and limbs, with D-shaped holes lining the bark
• Dying or balding upper crown
• Sparse leafage

How Arborists Manage and Control Bronze Birch Borer Infestations

Female bronze birch borers tunnel D-shaped holes beneath the crevices and cracks of the bark of a vulnerable birch tree. Colonies form as they lay eggs that turn into larvae after two weeks. These larvae have piercing tissues on their mouths that can tunnel into the vascular tissues of trees, robbing them of essential sugars and life-supporting nutrients.

Arborists control bronze birch borer and gloomy scale populations by eliminating diseased and dying branches before newly hatched larvae can damage tree phloem in early May. We might spray approved chemical pesticides like permethrin and bifenthrin to eliminate fully grown colonies.

Birch trees are beautiful but are easily stressed and short-lived, making them vulnerable to infestations in urban settings. Lawn trees that receive sparse moisture and nutrients require customized fertilization methods. Strategic planting is essential for avoiding infestations.

Get Expert Help Today

Learn more about bronze birch borer symptoms. Contact licensed tree care services by calling Rick’s PHC Certified Arborists at 610-840-2655 and asking for a free consultation.