Signs of Active Woodworm Infestation

You may not hear them. You may not see them. But woodworm could be quietly eating through the timber in your home right now.

These insects often stay hidden in loft beams, under stairs, or inside old furniture, where they cause damage without you knowing.

You usually only discover an active woodworm infestation once the signs start to show. Maybe a floorboard feels soft underfoot. A stair tread gives way. Or a chair leg suddenly cracks. By that point, the damage is already done, and the repair costs are mounting.

If that’s something you’d rather avoid, this guide is for you. You’ll learn how to spot the early signs of woodworm and what to do before it spreads any further. Let’s get started.

What is Active And Inactive Woodworm Infestation?

An active infestation means the woodworm (actually beetle larvae) are still alive and feeding inside your wood right now. They’re tunnelling through the timber, weakening it from the inside out.

An inactive infestation means the woodworms were there in the past, but they’ve long since matured, left the wood, and died. The damage remains, but it’s not getting worse.

Active vs Inactive Woodworm Infestations Comparison Table

How Does a Woodworm Infestation Start?

It starts with a beetle. An adult female finds a piece of timber she likes — usually slightly damp and soft enough for her larvae to chew through. She lays her eggs in tiny cracks, under loose paint, or inside old exit holes.

When those eggs hatch, the larvae bore into the timber and start feeding. They live hidden inside the woods for years, slowly making their way deeper. You won’t see them. You won’t hear them. But they’re there, turning strong wood into a maze of tiny tunnels.

At some point — two, three, maybe even five years later — they’ll pupate and emerge as adult carpet beetles. That’s when you spot the round exit holes and the fine-bore dust called frass. But here’s the catch: if you’re seeing that now, it means they’ve already done years of work inside your wood.

What Causes Woodworm Infestation?

There’s no single reason. It’s often a mix of conditions that make timber inviting:

• Damp timber — woodworm larvae love moisture. Leaky roofs, rising damp, or poor ventilation can make timber soft and appealing.

• Old or untreated wood — timber without a protective treatment is easier to chew through. Antique furniture is a classic target.

• Poor airflow — lofts, cellars, and crawl spaces often trap damp air.

• Previous infestation sites — old exit holes can be reused by beetles for laying new eggs.

• Second‑hand timber or furniture — woodworm can hitch a ride straight into your home from somewhere else.

Moisture is often the deciding factor. In a dry, well‑ventilated home, woodworm infestation is far less likely. But give them damp timber, and they settle in for the long haul.

Where Does Woodworm Infestation Occur?

Woodworm will take just about any piece of timber it can get into, but in UK homes, there are a few favourite spots.

• Roof timbers – Lofts often have poor ventilation. A slipped tile or small leak is all it takes to let in damp, and that’s an open invitation.

• Floorboards and joists – Especially on ground floors, where air circulation is poor. Moisture rising from the soil can keep timber slightly damp for years.

• Furniture – Antique or second‑hand furniture is a classic carrier. Sometimes you bring the problem in without knowing it.

• Staircases and banisters – These are often overlooked until the damage is advanced.

• Door and window frames – Condensation or water ingress around these can keep the wood soft.

Which Homes are at Risk of Woodworm Infestation?

You might think woodworm only affects old cottages with creaky floorboards, but that’s a myth. Modern houses aren’t immune. Any home with untreated or damp timber is at risk.

High‑risk situations include:

• Homes with poor ventilation, especially in lofts and under floors.

• Properties with ongoing damp problems.

• Houses with unheated rooms where condensation lingers.

• Storage of second‑hand furniture without inspection.

• Timber outbuildings or sheds in constant contact with damp ground.

Signs of Active Woodworm Infestation?

If you spotted signs of woodworm infestation in your property, here is how to tell if it’s an active or historic infestation:

• Fresh exit holes – Small, round holes (about 1–2 mm) with clean edges. The wood around them often looks lighter than the surrounding timber.

• Frass (bore dust) – Fine, powdery dust that falls from holes or sits on nearby surfaces. Fresh frass is loose and dry, not clumped or hard.

• Powder on the floor – Small piles of pale dust directly under a damaged beam or furniture leg are a giveaway.

• Weakened timber – Press the wood gently. If it crumbles or feels soft under light pressure, larvae may still be feeding inside.

• Live beetles – In summer months, you might spot them near windows or emerging from the timber.

• Hollow sound – Tap the timber lightly. If it sounds hollow, it may have been eaten away inside.

How Serious Is an Active Woodworm Infestation?

Woodworm is a serious threat to your home’s structure. The larvae burrow deep into timber and feed on it for years. What may seem like a few harmless holes on the surface could mean the wood is crumbling inside. Floorboards can snap underfoot. Roof timbers can weaken. Joists and beams can become dangerously unstable.

In older homes, where timber plays a major structural role, an untreated infestation can lead to full structural failure. This is not a problem you can afford to leave. It only gets worse with time and can cost thousands to repair.

How to Treat Active Woodworm Infestation

Treatment depends on the extent of the infestation and where it is. Some small, surface‑level issues in furniture can be handled at home. Structural timber infestations almost always need professional treatment.

Home Remedies for Minor Cases

• Freezing small items – If the infested wood is portable and small enough (like a chair or decorative item), wrapping it in plastic and freezing it for several days can kill larvae.

• Boron‑based treatments – Available at DIY stores, these penetrate timber and kill active larvae. They work best for light, accessible infestations.

• Heat treatment – For smaller pieces, heating the wood to around 55°C for an hour or more will kill larvae. This isn’t always practical for large items.

Professional Treatments

• Insecticidal sprays and gels – Applied by licensed professionals, these penetrate deep into the timber to kill larvae.

• Fumigation – For severe or widespread infestations, professionals may use gas or mist treatments to reach every part of the timber.

• Timber replacement – If the wood is badly weakened, it may need to be removed and replaced to restore strength.

How Long Does it Take to Treat Woodworm?

Small, isolated infestations in furniture can be dealt with in a matter of days. Freezing, heating, or applying a surface treatment works quickly once started.

For structural timber in a home, treatment can take longer. Sprays and gels work over several days to penetrate the wood and kill larvae. Fumigation or large‑scale treatments may require you to vacate the property for a short time.

The bigger factor is when you start. The sooner you treat an active woodworm infestation, the faster it’s resolved and the less damage you’ll face.

Wait too long, and the repair work becomes the slowest and most expensive part.

How Can You Prevent Woodworm Infestation?

Prevention is always cheaper than treatment. And the good news? Most of it comes down to keeping your timber dry and well‑ventilated.

• Control moisture – Keep your home well‑ventilated, especially in lofts, basements, and under‑floor spaces. Fix leaks promptly.

• Treat vulnerable timber – Use a wood preservative on untreated timbers, especially in sheds, garages, or exposed areas.

• Inspect regularly – Check for holes, frass, and soft spots at least twice a year. Pay extra attention after damp winters.

• Check second‑hand furniture – Inspect before bringing it indoors. Look for exit holes and shake gently over a light surface to spot falling dust.

• Manage storage conditions – Avoid keeping wooden items directly on damp floors or pressed against cold external walls.

Will Woodworm Infestation Come Back After Treatment?

If treatment is done properly, the chances are low — but not zero. Professional insecticidal treatments usually kill all active larvae in the treated timber, and reputable companies back their work with a guarantee.

That said, a new woodworm infestation can occur if conditions are still favourable. Damp timber, poor ventilation, and untreated wood can all invite beetles back over time. This is why prevention after treatment is just as important as the treatment itself.

What to Do if Woodworm Infestations Come Back?

If you spot fresh frass or new holes after treatment, act quickly. Don’t assume it’s a leftover from before — confirm it.

• Re‑inspect – Look for multiple signs: fresh dust, clean‑edged holes, and soft timber.

• Contact the treatment provider – If your treatment came with a guarantee, they should return to re‑treat at no extra cost.

• Address the cause – Check for damp or poor ventilation and fix it to prevent a cycle of re‑infestation.

Final Thought

A woodworm infestation rarely starts with anything dramatic. It’s quiet, hidden, and easy to miss — until it isn’t. By the time the signs are obvious, a lot of the damage has already been done.

The best defence is a mix of awareness and action. Know where to look, check regularly, and deal with problems early. If you suspect an active infestation, confirm it quickly and treat it without delay.

Whether you tackle a small case yourself or bring in a professional for bigger jobs, the aim is the same: protect your timber now so you don’t face expensive repairs later.

Woodworm Infestation Question Answered