Household pests
Woodworm: signs, how serious it is and treatment
Woodworm is the larval stage of wood-boring beetles, most commonly the common furniture beetle, that tunnel through timber and leave round exit holes when adults emerge. Small, old, inactive damage is often harmless, but active infestation in structural timber needs a professional survey and treatment to prevent weakening.
- Also known as
- common furniture beetle, Anobium punctatum, wood-boring beetle
- Easily confused with
- old nail or screw holes, mechanical damage, deathwatch beetle and house longhorn (less common, more serious)
- How serious
- Variable: old damage is often harmless; active structural infestation is serious
- Typical cost
- A timber survey often runs from around 150 to 350 pounds; treatment varies widely with the area affected
How to identify woodworm
The classic sign is a scatter of round exit holes, around 1 to 2mm across for the common furniture beetle, in furniture, floorboards, joists or roof timbers. Fresh holes look clean and pale inside.
The key sign of an active infestation is frass: fine, gritty, biscuit-coloured dust that falls from the holes onto surfaces below. You may also see adult beetles in spring and summer, or weak, crumbling timber. Old grey holes with no fresh frass often mean the infestation is long dead.
How serious is it?
Variable: old damage is often harmless; active structural infestation is serious
The Property Care Association notes that not all woodworm is active and not all active woodworm needs the same response, so identifying the beetle and whether it is still active matters before any treatment.
Common furniture beetle in dry, sound timber is usually slow and manageable. The concern is active infestation in structural timber, or signs of the rarer deathwatch beetle or house longhorn beetle, which can seriously weaken floors and roofs and call for specialist assessment.
How to fix it yourself
- Work out if it is active: lay paper or tape under the holes and check over weeks for fresh frass, or watch for new clean holes in spring and summer.
- Reduce damp. Many wood-borers need damp timber, so improving ventilation and fixing leaks makes timber less hospitable.
- Treat small, accessible, non-structural items (such as furniture or a few floorboards) with a proprietary woodworm treatment, following the label exactly.
- Do not paint over or hide damage you have not assessed, as this can mask an active problem.
When to call a professional
- Any infestation in structural timber such as joists, roof timbers or load-bearing floors.
- Signs of active infestation over a wide area, or suspected deathwatch beetle or house longhorn beetle.
- When buying or selling a property, where a documented survey is needed.
Who to call
- A Property Care Association (PCA) member surveyor for an independent timber survey and treatment specification.
- A qualified surveyor or structural engineer if timber strength is in doubt.
Indicative cost: A timber survey often runs from around 150 to 350 pounds; treatment varies widely with the area affected. Prices vary by area, severity and access, so always get a written quote.
Frequently asked questions
How do I know if woodworm is active or old?
Active woodworm produces fresh, pale frass (fine wood dust) below clean new exit holes, usually in spring and summer. Old, inactive holes are grey inside with no fresh dust. Taping paper under the holes and checking over a few weeks is a simple way to test.
Is woodworm a serious problem?
It depends on the beetle, the location and whether it is active. The Property Care Association notes not all woodworm needs treatment. Old damage in furniture is often harmless, but active infestation in joists, floors or roof timbers can weaken them and needs professional assessment.
Do I need a survey for woodworm?
A survey is worth it for structural timber, a widespread or active infestation, or when buying or selling a property. A Property Care Association member surveyor can confirm the beetle, whether it is active, and what treatment, if any, is actually required.
Does woodworm mean my house has damp?
Often, yes. Many wood-boring beetles prefer damp or previously damp timber, so woodworm can point to a moisture problem. Fixing damp and improving ventilation is an important part of stopping it returning.
Sources
Editor, HomesAndHedge
Oliver leads HomesAndHedge's editorial coverage of home and garden problems. He researches and writes the plain-English explainers on pests, invasive plants, damp and mould, drainage and wildlife, drawing on guidance from bodies such as the Property Care Association, the RHS and the NHS, and is clear about when a job needs a qualified professional.
Last reviewed: 8 June 2026