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IPM Scouting in Woody Landscaple Plants

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Twolined chestnut borer - Agrilus bilineatus
IPM scouting in woody landscape plants > twolined chestnut borer
Twolined chestnut borer is primarily a pest of oaks. Adults, found from mid-June through September, are rarely seen. They lay their eggs in bark fissures and cracks around late June or early July. Larvae burrow into the bark and feed in the phloem. Larval development may take up to two years. Emerging adults chew a D-shaped exit hole in the bark. Injury symptoms begin in the upper part of the crown and proceed downward.

Trees exhibit sparse foliage, chlorotic leaves and dieback. D-shaped exit holes (about 1/8 inch in diameter) may be visible in the upper part of the tree. Long, winding galleries packed with frass can be found under the bark in areas where larvae are present.

Management: Stressed trees are much more prone to injury. Help keep trees healthy through proper site selection and watering; protect from construction injury. Once injury occurs, damage may be pruned out if it isn’t too extensive.
Twolined chestnut borer
Adult is a metallic wood boring beetle (Buprestidae) 10-13 mm long.
Damaged tree Larvae Galleries of twolined chestnut borer
A layer-cake effect of dying and live branches occurs on oaks infested with twolined chestnut borers. Larvae of buprestids are commonly known as flat-headed borers due to the broad, flattened thorax, as shown on the larva in the photo. Bark removed to show galleries of twolined chestnut borers.
Additional information
This information was developed from A Pocket IPM Scouting Guide for Woody Landscape Plants by Diane Brown-Rytlewski. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension (publication E-2839).
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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Updated 7/10/07