Guides
What to Do If You Find Woodworm
Found small round holes in your timber? Here's exactly what to do next — how to check if it's active, whether you need treatment, and how to get help fast.
By The WoodwormTreatmentHQ Team · Updated 2 June 2026
Finding small round holes in a floorboard, a roof joist or a piece of furniture is unsettling. Your first question is usually the same as everyone else’s: is this serious? The honest answer is — it might be nothing, or it might need prompt attention. This guide tells you exactly what to do next.
Step 1: Don’t panic — old holes don’t mean active woodworm
The most important thing to understand before you do anything else: not every set of holes means you have a live infestation. Wood-boring beetles leave behind their exit holes permanently, and timber from decades ago can still show the scars of an infestation that ended long before you bought the property.
Old, inactive holes are extremely common in Victorian and Edwardian homes. They require no treatment. The question you need to answer first is whether the woodworm is active right now — and that comes down to a few simple checks.
Step 2: Check for these signs of active woodworm
An active infestation looks different from an old one. Look for:
Fresh frass (bore dust) — Fine, cream-coloured powder beneath or around holes. It looks like fine sawdust or talc. Old frass is compacted and grey; fresh frass is loose and pale. Tap the timber gently and check what falls. This is the most reliable active indicator.
Clean, pale-edged holes — New exit holes have crisp, pale edges. Old holes are weathered, darkened and rounded at the rim. If you can see into a hole and the interior wood is pale, it is recent.
Live or dead beetles — Adult beetles emerge from May to September. Finding small brown beetles (3–5mm) on windowsills near affected timber, or in cobwebs close by, confirms recent activity.
Weak or crumbling timber — Press a screwdriver gently into the wood. If it sinks easily, the interior may be heavily tunnelled. This usually means a long-standing active infestation.
Read the full signs of woodworm guide for photographs and detailed identification of each sign.
Step 3: Identify where the holes are
Where the holes are matters almost as much as whether they’re active.
Floorboards and floor joists — The most common location. Infestation here can weaken the structural floor over time. Check the underside of boards and exposed joist faces in the cellar or sub-floor void.
Roof timbers and rafters — Lofts are high-risk because they’re rarely disturbed, stay cool and can be damp. A heavily infested rafter may feel soft or crumble at the edges.
Furniture and antiques — Common furniture beetle frequently attacks old furniture. This is less structurally serious but can ruin an antique piece. See our guide to woodworm in furniture.
Structural beams — Old oak beams may show larger 3mm holes from the death watch beetle. This species is slower-moving but more damaging and requires specialist treatment.
Step 4: Do the tissue-paper test (for floor and roof timber)
If you want to check without calling anyone first, tape a piece of white tissue paper over the suspected area in early spring (March–April). Leave it for two to three weeks. When adult beetles emerge in May–June, they push through the tissue, leaving a hole. This confirms active flight-season emergence.
This test only works in spring before the flight season begins. At other times of year, fresh frass is a more reliable indicator.
Step 5: Decide whether to DIY or call a professional
When DIY treatment is reasonable:
- Isolated infestation in a piece of furniture or a small area of exposed timber
- Easy access to the affected wood
- Active holes are superficial and not structural
- You’re confident identifying the species as common furniture beetle
DIY permethrin-based woodworm killers (Permagard, Rentokil, Ronseal) work well in these situations. Apply liberally to all bare timber surfaces, including adjacent areas. Read our best woodworm treatment products guide for recommendations.
When you need a professional:
- Holes are in structural timber — joists, rafters, lintels, beams
- The wood feels soft, hollow or crumbles when pressed
- Infestation covers a large area
- You’re selling or buying a property (mortgage surveys require a professional certificate)
- You suspect death watch beetle or house longhorn beetle (larger holes, old oak, or Surrey property)
- You’ve tried DIY treatment and the infestation has returned
A professional survey confirms the species, whether the infestation is active, and the exact scope of treatment needed — before any money is spent on treatment.
Step 6: Book a free woodworm survey
Most homeowners who call us haven’t decided yet whether they need treatment. That’s exactly the right moment to book a survey. A qualified surveyor visits, inspects the affected timber, identifies the species and confirms whether the infestation is live or historic. For most domestic properties, the survey is free.
If treatment is needed, you receive a fixed written quote before anything happens. There’s no obligation to proceed, and if the infestation is historic we’ll tell you clearly — even if it means we don’t get the job.
Book your free woodworm survey →
What happens during a woodworm survey?
The surveyor will:
- Inspect the affected areas and any timber nearby that may be at risk
- Confirm active or historic infestation using frass, hole condition and timber soundness
- Identify the species (this determines the correct treatment)
- Check for associated damp or rot (woodworm rarely travels alone)
- Provide a written report and, if treatment is needed, a fixed quote
Most residential surveys take 30–60 minutes. For loft spaces and sub-floors, the surveyor needs access to those areas — so have a step ladder to hand.
How treatment works
If treatment is needed, the most common method for the common furniture beetle is a water-based permethrin spray applied to all affected and at-risk timber surfaces. It is touch-dry within a few hours, low-odour and safe for occupied homes once the area has ventilated.
For structural timber with deep infestation or hard-to-reach joist ends, boron gel or paste may be used alongside the spray. In rare cases where access is very restricted, fumigation treats the whole void in one application.
Treatment typically takes half a day to a full day. Every job carries a 30-year guarantee and a written treatment certificate — which is required by mortgage surveyors and useful for future property sales.
Get professional help
If you’ve found what looks like woodworm, the fastest way to get clarity is a free survey. There’s no cost, no obligation and no pressure — just an honest answer about whether you have a problem and what, if anything, needs doing.