Chestnut (Castanea)-Shothole borer

Xyleborus dispar

Pest description and crop damage An ambrosia-type bark beetle that is small and generally black or dark brown. This is a European beetle first found in Washington in Clark County in 1901. There are up to two generations per year. They overwinter as adults in the host trees, often with their dark rear ends visible in their galleries. Adults bore into sapwood. Males are smaller than females, and flightless. The females initially move to new, generally stressed trees, then emit an aggregation pheromone that attracts more beetles. Arriving beetles land on infested and nearby trees. New plantings are especially susceptible to attack.

Scouting and thresholds Monitor flights of beetles with ethanol-baited funnel traps from February through the end of summer. Look for fresh sawdust and sap on trees to detect injury. Yellow magnolias are very susceptible and can act as an indicator plant for beetle activity. Even one hole in a tree reduces its quality and most growers treat when beetle flights first occur on warm summer days in late winter or spring.

Management-cultural control

Keep trees vigorous. Rogue and destroy infested trees immediately.

Management-chemical control


Control options are poorly understood at this time. Early spring applications are required. Apply materials to the trunk and lower limbs. Avoid contacting foliage.

For more information

Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 250).

PNW Nursery IPM: European shothole borer (