Fresh-looking exit holes and recent frass can indicate current activity, while older holes may be historic. Species, timber condition, moisture and evidence of recent emergence should be assessed before treatment is recommended.
Signs worth recording
- New frass below holes or on a recently cleaned surface.
- Live or dead adult beetles found during the relevant emergence period.
- Fresh-edged holes, damaged sapwood or galleries exposed in a break.
- Timber that is damp, softened or affected by fungal decay as well as holes.
Why holes alone are not proof
Flight holes can remain for decades after an infestation has ended, and dust can be dislodged by vibration or building work. Paint, restricted access and insulation can also make the extent difficult to judge. Treatment should not be specified solely because old holes are visible.
The inspection considers the accessible evidence, species where possible, moisture source and whether timber has lost strength. If structural capacity is in doubt, opening-up or advice from a structural engineer may be required before repair.