Woodworm treatment: signs, inspection, costs and how it is done
Woodworm treatment comes into view as soon as you discover small round holes and fine bore dust in timber. Woodworm is not a worm but the larva of a beetle that spends years eating tunnels through beams, floorboards and furniture before the adult emerges. In the Netherlands it is usually the common furniture beetle, and in old buildings also the death watch beetle. The damage grows slowly but steadily, and in load-bearing beams and roof structures it can eventually affect the strength of the timber.
In this guide you will read how to recognise woodworm, how to check whether the infestation is still active and when a professional woodworm inspection and treatment is needed. You will also find a cost indication for 2026 and tips to prevent new infestation. To hire a woodworm specialist straight away, see the top 3 pest controllers in your city.
Recognising woodworm: holes, bore dust and species
The best-known sign is round exit holes of 1 to 2 millimetres in the wood. With the common furniture beetle (gewone houtworm) they are small and neatly round; the death watch beetle (bonte knaagkever) makes larger holes of 2 to 4 millimetres and is found almost only in old, damp hardwood such as oak beams in historic buildings. Fresh bore dust is the main sign of activity: light, fine piles of powder under or beside the holes. Note: not every old hole means there is still woodworm inside. The larvae live in the wood for 2 to 5 years and the beetles emerge in spring and summer, so holes can date from years ago. Old holes are dark and dusty inside, new holes are light with a sharp edge.
Woodworm treatment: DIY or call a professional?
A loose piece of furniture or a shelf can be tackled yourself with a consumer woodworm product that you let soak into the wood, or by putting the item in the freezer for a few days. As soon as it concerns beams, floors, the roof structure, a staircase or a large surface, professional treatment is the sensible choice. A professional can judge whether the infestation is active, which species is involved and whether the timber is still strong enough. They may also use professional biocides thanks to a professional competence certificate (KPMB) and have equipment to get products deep into the wood. If in doubt whether the woodworm is still active, have a woodworm inspection carried out before booking a treatment.
How professional woodworm treatment works
A woodworm specialist starts with an inspection: they examine all timber parts, identify the species from the holes and bore dust, measure the moisture content of the wood and probe the beams to check their strength. You receive a report with the extent of the infestation and a plan. During treatment the wood is first cleaned and, where necessary, the damaged surface is removed. A product with a long residual effect is then sprayed or brushed onto the wood so that it soaks in deeply; thick beams are sometimes injected as well. With the death watch beetle, tackling the source of damp is part of the job, because without moisture and fungus this beetle does not survive. A good pest controller follows IPM: treat only what is active, remove the cause and often give a multi-year guarantee on the treated timber.
Woodworm treatment costs: what you pay in 2026
As an indication, a woodworm inspection in 2026 costs €75 to €150, including VAT. The treatment itself is usually priced per square metre of timber surface: expect €15 to €35 per m², depending on accessibility, the product and whether injection is needed. For an average home the total often comes to between €300 and €1,500. Replacing timber that is too badly damaged falls outside pest control and is done by a carpenter or contractor. Ask for quotes stating the number of square metres, the product used and the guarantee.
Price indication 2026 per pest
| Pest | Indication | Notes |
|---|---|---|
| Woodworm inspection | €75 to €150 | Including VAT, sometimes deducted if you go ahead with treatment |
| Treatment per m² of timber | €15 to €35 | Spraying or brushing, injecting thick beams may cost extra |
| Total for an average home | €300 to €1,500 | From a single floor to a complete roof structure |
| Replacing badly damaged timber | on quote | Via a carpenter or contractor, outside pest control |
Indications for private customers, including VAT, based on public rates in 2026. The actual price depends on severity, accessibility and the number of visits. Always ask for a fixed price in advance.
Preventing woodworm: dry timber and regular checks
Woodworm thrives in damp, poorly ventilated timber. So make sure the loft, crawl space and shed are well ventilated and deal with leaks, rising damp and condensation quickly. Treat bare timber in the loft and shed preventively with a stain or varnish, because a sealed surface makes it hard for the beetle to lay eggs. In spring and summer, the beetles' flight season, check beams, staircases and floorboards for new holes and fresh bore dust. A yearly look at the roof structure prevents a new infestation growing unnoticed.
