Flat Headed And Shothole Borers

Flat-headed and shothole borers are wood-boring beetles that attack weakened, dying, or recently dead Western red cedar and other conifers in Western Washington. You will see small exit holes in bark and frass accumulation around entry points. Damaged trees show decline in vigor; borers follow stress rather than cause it. Multiple generations can develop in severely stressed wood.

Prevention is the best management through maintaining tree health and proper watering. Once borers are established, no effective chemical control exists. Remove and destroy infested wood; cut into healthy sapwood to expose galleries and disrupt borers. Firewood should be burned or chipped promptly to prevent beetles from escaping to nearby trees. Avoid creating fresh wounds on susceptible species during seasons when beetles are active.