Signs of Woodworm: How to Tell If You Have an Active Infestation

Woodworm is the generic term for the larvae of several wood-boring beetle species. The most common in UK properties is the Common Furniture Beetle (Anobium punctatum). Here's how to tell if you have an active infestation.

Signs of Woodworm

1. Round exit holes — About 1–2mm in diameter, the classic sign of adult beetles having emerged. Found in floorboards, joists, furniture, and roof timbers.
2. Bore dust (frass) — Fine, powdery dust beneath exit holes is the clearest sign of active woodworm. Old infestations leave dry, hard dust; active ones leave fresh, pale dust.
3. Weak or crumbling timber — Heavily infested wood becomes structurally compromised, particularly in joists and floorboards.
4. Adult beetles — If you see small brown beetles (1–5mm) around windows in summer, these could be emerging woodworm beetles.

Active vs Old Infestation

Not all woodworm requires treatment. An old, inactive infestation may have caused its damage decades ago. The key question is whether it's still active. Fresh bore dust, pale holes, and sightings of beetles in spring/summer are the best indicators.

Treatment

Active infestations are treated with specialist insecticidal fluid applied by brush or spray. Structural damage is assessed and repaired as needed. Shadbolt Plastering provides woodworm treatment and timber surveys across South London and Surrey.