Bronze Birch Borer

• Adult borers are thin, copper-colored beetles less than an inch long, but they are not commonly seen. They lay their larvae beneath the bark of birch trees. The larvae is small, white and grub-like, and once inside the tree they feed on the tissue the tree uses to transport photosynthesized food from the canopy to the roots. The roots of the tree starve and the tree is unable to get enough water, which leads to it dying back.
  
  

Borer Symptoms

• The dying back usually begins at the upper crown of the canopy, with leaves that yellow in midsummer and then turn brown and die. In addition to the browning of leaves, the trunk of the tree will begin to show ridges from the feeding activity of the larvae, and there will be "D" shaped holes from the adult bronze borers.
  
  

Controlling Bronze Borers

• Healthy trees are the best way to keep out bronze borers. Trees that don't get enough water, nutrients or sunlight are working overtime to keep themselves going and don't have the resources to fend off pests. Choose birch trees that are resistant to borers -- such as the crimson frost birch or heritage birch -- and plant them in suitable sites.
  
  

Birch Tree Maintenance

• Birches like cool, moist soil, but their leaves need full sunshine throughout the day. Planting on the east or north side of a home is generally a wise idea. Slow, deep watering is the best practice, as well as mulching the tree's root system, fertilizing when there is a lack of nutrients and only light pruning. Pruning should not be done between May and July because borers are attracted to pruning wounds.