Harmful Insects

Two-Lined Chestnut Borer

Oak trees dying from the top down and exhibiting the symptoms of drought may be infested with the two-lined chestnut borer, Agrilus bilineatus (Weber). This insect kills or damages hundreds of red, black, white, and bur oaks in Minnesota every year. The two-lined chestnut borer causes the disfigurement or death of oaks through successive attacks on the branches and stems. Larval feeding destroys the nutrient and water conducting tissues, which, in turn, kills the portion of the tree beyond the point of attack. Damage may result in the death of a single limb, half the crown, or the entire tree. It is important to remember that oaks are also subject to oak wilt, which has similar symptoms. Proper diagnosis is essential to choosing appropriate control procedures.

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