General Description:

The Two-lined Chestnut Borer (Agrilus bilineatus) belong to a group of beetles known as Jewel or Metallic wood boring beetles. These beetles are variable in size and color but generally have almond shaped bodies and complete their life cycles partially by boring in trees and feeding on the inner bark tissues.

Studies have shown healthy vigorous trees are relatively immune from borer damage. Oaks under stress from drought, flooding, other insects, or construction damage are most at risk for attack.

Identification:

The Twolined Chestnut Borer is a slender beetle up to one half of an inch long and has two distinct markings on its back elytra (back wing coverings). Infested trees will have pockets of bark that will have tunnels under them and may sound hollow. Exit holes can be seen after the adult emerges form the tree in the summer time.

Distribution:

The species can be found where-ever its host range is; mostly in the Eastern two-thirds of the United States.

Susceptible Species:

Oaks including Chestnut, Scarlet, White, Northern Pin, Post, Black, and Burr Oak. American Chestnut is also susceptible though a rare species in forests today.

Symptoms:

Infected trees may be recognized by sparse, small and discolored foliage. Branches usually die-back from the top down.

Prevention and Treatment:

Once the Two-lined Chestnut Borer is established there is no effective control. Keeping the trees healthy by fertilizing, spraying, and properly watered is the key to providing conditions less favorable to the insect.

For a pdf copy of this factsheet: Twolined Chestnut Borer