Red Oak Borer vs. Carpenter Ants: Correct Identification Matters

A homeowner found quarter-inch "tubes" at the base of a red oak with large ants entering holes. Initially thought to be carpenter ants, the evidence pointed to red oak borers.

Carpenter Ants: Secondary Occupants

They nest in already-decayed wood, not healthy tissue. They don't kill trees but indicate existing decay. Control: dust insecticides (Sevin, rotenone) into cavities; baits (Terro, boric acid) for satellite colonies near homes.

Red Oak Borer: Primary Pest

The "tubes" are larval frass (excrement). Borers have a 2-year cycle with distinct external signs:

• Year 1 fall/winter: fine frass
• Year 1 spring: wet spots, medium frass
• Year 2 fall/winter: discolored bark patches, heavy frass
• Year 2 spring: wood slivers, oval exit holes

Treatment

1. Spray trunk with Onyx or Merit for borer control.
2. Fertilize with 10-10-10 at 1 lb per inch trunk diameter (fall) to reduce stress.

Key Insight

Borers attack stressed trees. Improving vigor is essential for long-term prevention.