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Pest Information

Bronze birch borer

Bronze birch borer

  • Latin Name: Agrilus anxius
  • Common Name: Bronze birch borer
  • Other Names: N/A

Pest Details

Bronze birch borer
Bronze birch borer


This is a native beetle in North America.


This serious pest restricts its attacks to various species of birch trees, and is particularly damaging to white-barked species such as European white birch and Paper birch. It prefers trees that are in weakened condition and may not successfully penetrate into the cambium in healthy trees that can fill the larval tunnel with sap. The life cycle takes 1 year in southern states and 2 years in cooler northern states. Adult beetles are active in early to mid summer, the females depositing eggs into crevices in the bark. The late stage larva overwinters and pupates in the spring.


Adult beetles average about 3/8 inch long and are narrow and cylindrical. The color is from deep olive green to black with metallic bronze reflection. The larvae are typical of flat headed borers, with elongate white bodies that are flattened, and with the second segment of the thorax behind the head wider than the rest of the body. The feeding galleries under the bark will be oval in profile and filled with the sawdust-like frass as the larvae moves along. Oval emergence holes of the adults will be found on the bark of infested trees.

Characteristicts Important to Control:

Control is difficult once the larvae are feeding within the tree, but they may be killed by systemic insecticides injected into the trunk. Adult beetles may be killed if contact insecticides can be applied to the trunk timed to the first presence of the adult beetles. Healthy trees are generally able to withstand the presence of some of the larvae, so good tree health is important. A number of parasitic wasps also help to reduce the numbers of larvae that survive in the tree.

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