Damage to wood

How to examine it

1. Tap along the timber with a screwdriver handle and listen. A hollow or papery note where the wood should sound solid marks damage below the surface.
2. Probe suspect areas with an awl or a screwdriver tip. Note how far it sinks and whether it follows the grain or cuts across it.
3. Collect any material that falls out onto white paper, so its colour and texture are visible.
4. Rub a little of it between finger and thumb. Flour-fine and free-flowing, hard six-sided pellets, or coarse fibrous shavings are three different insects.
5. Look for mud. Soil packed into galleries, or tubes on a nearby wall, changes the answer entirely.
6. Photograph the damaged member in context so the location, orientation, and extent are recorded, not just a close-up.

What else gets mistaken for this

• Old nail and screw holes, and holes left by a drill during a past repair. These are perfectly cylindrical, go straight in, and have no gallery behind them.
• Woodpecker damage, which is irregular, on the exterior, and often adjacent to carpenter bee galleries because the bird is after the larvae.
• Decay and wet rot, which softens and crumbles the wood without producing galleries, exit holes, or frass. A probe sinks in easily but nothing falls out.
• Shrinkage checks and seasoning splits, which run along the grain in straight lines and go nowhere.
• Old, inactive damage from an infestation resolved years or decades ago, which looks the same as current damage and is separated from it only by the clear-and-recheck test.

What this evidence cannot tell you

Damaged wood tells you which insect made the galleries. It does not tell you whether the infestation is still active — old damage from an infestation resolved a decade ago looks much the same as damage being made now. The test for activity is fresh material: clear the frass, mark the date, and see whether it returns within a fortnight. It also does not tell you the extent. What is visible on the surface of an accessible member says nothing about the timber inside a wall or under a floor, which is exactly why a written inspection finding covers only what was visible and accessible on the day.

What to do with what you found

Mud present means subterranean termites and the response addresses a colony in the soil. Hard six-sided pellets with no mud mean drywood termites and the response addresses infested timber. Flour-fine powder in hardwood means powderpost beetles and softwood framing is not at risk. Coarse fibrous shavings in damp wood mean carpenter ants, and the moisture source is the thing to find. In all four cases, photograph and record before anything is repaired or replaced, because removing the evidence removes the basis for any second opinion.

Common mistakes

• Repairing or replacing the timber before the evidence is recorded, which destroys the only basis for identification and for any warranty claim.
• Treating conducive conditions on an inspection report as a finding of infestation. They are a correction list, not evidence of insects.
• Assuming old holes mean an active problem. Sweep, date, and re-check before acting.
• Reading surface damage as the full extent. It rarely is.
• Applying a subterranean termite response to drywood damage, or the reverse. The two share almost nothing operationally.

Not sure?

Your county extension service will often identify a specimen at no cost, and that is more useful than a confident guess.

Start the identification key