Shothole borers are small (1/10" or less), brown to black, stubby-nosed beetles. Adults feed at the base of leaves or twigs. Later, they bore into the bark and lay eggs along a narrow gallery paralleling the grain of the wood. The white, legless grubs (bark beetles) feed by boring between the bark and sapwood, making narrow tunnels filled with sawdust-like frass (excrement). Feeding larvae can weaken or girdle trees. Larval galleries are typically at right angles to the first gallery, with the grubs pupating at the end of the galleries. The emerging adults leave tiny round "shotholes" in the bark, giving the beetle its name. Shothole borers are especially attracted to injured, stressed, or dying trees, but can also attack healthy trees. Fruit, ornamental, and forest trees and shrubs are attacked.

Management Options

Non-Chemical Management

Provide proper culture. Healthy trees are less likely to be attacked and more likely to survive infestations.
Prune out infested wood. Destroy prunings to reduce chances of reinfestation.
Whitewash trunks of young trees or purchase white plastic tree trunk wraps to prevent sunburn.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Burn prunings and keep trees in vigorous growing condition. Borer attack usually indicates trees are in unhealthy condition.

Images

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Caption: Shothole borer infestation holes Photo by: A.L. Antonelli
Caption: Shothole borer holes on apple Photo by: R.S. Byther
Caption: Shothole borer galleries Photo by: E.H. Beers
Caption: Bark beetle (very similar to shothole borer) Photo by: A.L. Antonelli

WSU Extension

Hortsense