Sawdust on Oak Tree: Borers, Not Carpenter Ants

Sawdust from an old oak wound with no visible ants suggests wood borers (beetle larvae), not carpenter ants. Borers exploit decay-softened wood; the living cambium under bark is unaffected.

Treatment & Tree Health

1. Spray trunk: Onyx or Merit (imidacloprid) on affected bark kills borers.
2. Fertilize: 10-10-10 at 1 lb per inch trunk diameter, spread to drip line, water in. Do before rain or irrigate. Repeat spring.
3. Monitor: Healthy trees compartmentalize decay. No need to fill cavities.

Why Not Carpenter Ants?

• Large ants (>3/8") forage visibly day/night.
• Frass is coarse, fibrous; borer dust is fine powder.
• Ants nest in voids; borers tunnel in wood.

Address stress (drought, compaction, damage) to prevent future borer attacks.