Twolined Chestnut Borer

Oaks are beautiful trees to add to any landscape, but can be a primary feeding ground to a pest known as the Twolined Chestnut Borer.

When are my trees at risk and what should I look for?

Twolined chestnut borer frequently attacks a variety of oak species including red, white, bur, scarlet, pin, black, chestnut, post and live oak trees.

The primary targets for a twolined chestnut borer are oaks that are damaged by drought, flooding, construction, or trees that are declining. Urban oaks that suffer stress from trunk or root injury, soil compaction, and changes in soil depth are also vulnerable to attack by this pest.

As the chestnut borer attacks a tree, wilted foliage will begin to appear on scattered branches during late summer. The foliage on these infested branches will turn brown prematurely and remain attached to the branches for several weeks before dropping. In severe cases, trees can be killed within the first year of attack. Typically, death will occur after two to three years of successive borer infestation.

The twolined chestnut borer will also leave a permanent visible record of its visit. They bore distinctive “D-shaped” exit holes about 1/5 inches wide in the bark.

It is possible to prevent these pests from invading your oak trees. Contact your local arborist to create a prevention treatment plan for your unique landscape. You can also view the full PDF here.

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