How to Manage Pests

Pests in Gardens and Landscapes

Pacific flatheaded borer—Chrysobothris malis

Adult flatheaded borers are hard, dark, mottled beetles with a bronze cast. The larvae are light colored and have a distinctive shape with a flattened enlargement just behind the tiny head.

Identification of species | Life cycle


Flatheaded borers attack aboveground portions of the tree that have been previously injured by sunburn or other causes. Tunnels excavated beneath the bark by the borer larvae may cause a wet sappy area on the bark of the main trunk, which may later crack open. Emergence holes 3/16 inch wide appear in early summer.


Keep trees healthy and vigorous. Protect young trees from sunburn with whitewashing. Remove and destroy infested wood immediately. Insecticide treatments are not recommended.

Pacific flatheaded borer larva
Pacific flatheaded borer larva

Damaged caused by the flatheaded borer
Damage caused by the flatheaded borer

Statewide IPM Program, Agriculture and Natural Resources, University of California
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