Treating Woodworm 

Quick navigation: 









WHAT ATTRACTS WOODWORM? (Common Furniture Beetles)







What is Woodworm?

Woodworm is the common term used to refer to the larvae of all wood boring beetles. There are several species found in the UK, but most of the damage is caused by the offspring of the Common Furniture beetle. 

evidence of woodworm

What does a woodworm look like?

Woodworm larvae are usually a creamy white colour and have curved bodies. It’s highly unlikely you’ll ever actually see woodworm larvae, as they stay hidden munching away on timber until they are fully-grown. Adult wood boring beetles look different depending on their species: the Common Furniture beetle is a brown winged beetle, typically 3-4mm in length. 

Life Cycle of Woodworm

There are four stages of woodworm development: egg, larva, pupa and adult beetle.

Adult female wood boring beetles like to lay eggs on or just under the surface of the wood in pores, cracks and crevices. Safe inside the timber, the larvae feed on the wood (and cause damage!) for several years until they pupate and hatch as beetles. When they have reached maturity the new generation of beetles leave the safety of the timber in order to breed, when the adult females are ready they look for a suitable wood surface on which to lay their eggs, the life cycle continues causing further damage.

Types of Wood Boring Beetles

Some of the most common wood boring beetles are: Common Furniture beetles, Deathwatch beetles, House Longhorn beetles and Powder Post beetles.

wood boring insect in timber

How to identify an Active Woodworm Infestation

It can be tricky to tell if you have an active woodworm infestation as the main damage is caused inside the timber and you’re unlikely to see any visible results for years. However, there are a number of tell tale signs that can help you identify a potential woodworm infestation:

-       Small round holes in your woodwork, typically 1mm to 2mm in diameter

-       Fine, powdery dust around these holes (known as frass)

-       Crumbly edges to boards and joists

-       Tunnels within the timber

-       Weak or damaged timbers or flooring

During the summer months (woodworm season is May to October), you may also spot adult wood boring beetles emerging from holes within the timber. Once a wood boring beetle has chewed itself out of hiding, it instinctively heads for light. So check for live or dead beetles around a suspected woodworm infestation and on the windowsills. Steely Blue beetles are the main predators of the Common Furniture beetle, so if you see them wandering around it’s probably because they’ve found a good food source close by.

Exit holes are probably the most obvious sign, but they do not occur until the adult beetles are ready to leave the timber, years after hatching as woodworm larvae. So it’s good practice to look for signs of frass on the back or underside of old furniture.

Finding holes and frass on your furniture or flooring isn’t always a cause for concern, they might just be signs of a previous woodworm infestation which has long been dormant. If you are unsure, it’s best to consult a woodworm specialist.

How to tell if woodworm are active?

Judging whether the damage you’ve found is an active woodworm infestation or not is always the hard part.

One popular method for testing for an active woodworm infestation is filling the exit holes with beeswax or tissue paper, leaving it for a year and seeing if any adult beetles bore through in the next year. Whether or not you give this a go, it’s always best to talk to a specialist before going ahead with any treatment.

Where You Can Find Woodworm?

Woodworm can be found in all manners of wood surfaces including:

- Floorboards

- Furniture

- Joists/beams

- Roof timbers

- Painted wooden surfaces

- Wooden tools

- Joinery and structural timbers

- Decorative woodwork

- Musical instruments

woodworm in timber structure

What Attracts Woodworm?

Different species of wood boring beetles like different types of wood. Some prefer softwoods like pine, spruce and cedar. While others prefer hardwoods such as oak, ash and mahogany.  All wood boring beetles like wood that is damp, because it’s easier to chew!

The Common Furniture beetle can be found in both softwoods and hardwoods. Though it has been found in many places, it generally prefers damp floorboards, loft timbers and furniture that has worn or no varnish at all.

Female Furniture beetles tend to choose hardwoods with a moisture content of 28% or higher to give their larvae the best chance of pupating into adults. However, woodworm can be found living in timber down to 12% moisture content. The dryer the wood gets the harder it becomes for them to feed.

Common Furniture larvae will only eat the outer section or ‘sapwood’ of a tree. This is because it has more nutrients and is toxin-free, unlike the inner ‘heartwood’ of timbers like pine and oak. If your furniture is made from good quality heartwood, you are at much lower risk of getting a woodworm infestation. Sapwood is normally lighter than heartwood so you can spot where the high-risk areas are.

woodworm grub close up

Woodworm Grub by Dazzo­­

Less Common Species of Woodworm and Different Wood Types 

Deathwatch beetles prefer hardwoods such as Oak, Elm and Mahogany that have been softened by fungal decay. These are most often found in older buildings and antique furniture. These beetles are most common in central and southern England and are known for the distinctive tapping noise the adult beetles make when attracting a mate.

House Longhorn beetles are mainly found in the south east of England, and are particularly common in north west Surrey. The House Longhorn beetle is the most damaging wood boring insect. It attacks the sapwood of dry softwood and grows up to 30mm long. They leave exit holes of up to 10mm in diameter.

These beetles love partly seasoned softwoods including pine, spruce and fir, and are most commonly found in roof timbers. Larvae produce large quantities of frass containing small pellets, which leave a blistered appearance on the surface of the wood. The larvae can seriously damage timber within their growth period, entirely destroying the sapwood and leaving only the veneer.

How serious is Woodworm Infestation?

The extent of damage caused depends on the species, the size of the infestation, and what it is that has been infested. Not all woodworm is harmful. However, if left untreated over time, woodworm can seriously weaken timber, causing severe damage within its structure. 

House Longhorn Beetle is known as the most damaging species, but any major infestation should be checked by a professional.

woodworm in joists

How to prevent woodworm

Though it’s difficult to keep woodworm out completely, you can definitely make your home less appealing by: 

-       Keeping all wood dry

-       Keeping your home heated and well ventilated

-       Buying furniture made from good quality hardwood

-       Sealing wood with varnish

-       Carefully checking for signs of woodworm when purchasing antique or second-hand furniture

-       Removing infected wood from your home

-       Replacing infected timbers

-       Using flytraps to catch and contain adult wood boring beetles, hopefully before they have a chance to mate!

How to get rid of woodworm

Before treating any kind of woodworm, it’s extremely important to correctly identify the type of woodworm you’re dealing with. If you are unsure, it’s always best to consult a specialist.

If your woodworm problem only affects small items such as furniture, you can effectively treat it yourself using the right techniques and treatments.

You can easily treat Common Furniture beetles with a brush, dip or spray application of a Permethrin-based woodworm treatment on all timbers affected by woodworm. As a precaution you should also treat any close by timbers to protect against future outbreaks. Don’t forget to re-paint and re-varnish treated surfaces when they are dry.

Death Watch beetle infestations occur deep within a timber, so it is essential to treat by injection as well as a surface treatment. This can be done by injecting woodworm treatment spray into the exit holes left by the adult beetles. Or it can be done by drilling into the danger zone and filling the wood with a paste or gel woodworm treatment. The larvae of the Death Watch beetle often causes more harm than the Common Furniture beetle, so it’s good to check with a professional before going ahead with any treatment.

deathwatch beetle

Death Watch Beetle by Gilles San Martin

If you suspect you have a House Longhorn woodworm infestation it’s always best to consult a specialist. All timber within the building will need to be treated and inspected for its structural integrity. If your timber is free from severe structural damage and the infestation is minor, it may be safe to go ahead and tackle it with the same treatments and methods you would use to treat Death Watch beetles. But you must be very careful with this species of woodworm.

A professional should treat any severe infestations that has caused extensive damage.

Woodworm Treatments

Permagard Woodworm Killer (Ready to use) is perfect for treating woodworm caused by Common Furniture beetles. It contains Permethrin, which is effective against all the life stages of wood boring insects. Other treatments can only target one life stage.

Our ready to use woodworm killer has been specifically designed to protect furniture, flooring, structural and other timbers. It is designed to be rapidly absorbed into the wood giving higher levels of penetration. It is odourless and can be applied either by brush or low-pressure spray to give long lasting protection. And at just £9.50 for five litres you save over a third when you buy our ready to use Woodworm Killer online.

Lignum Insecticide Pro is great for treating Death Watch Beetle. Once diluted in water, this high-strength concentrate offers long lasting protection preventing further re-infestation. When injecting timber, Lignum Dual Purpose Timber Gel offers deeper penetration than liquids ensuring maximum protection. Always check with a specialist if you are unsure which method to use.

Click here to view our full range of woodworm treatments, and please give our experts a call on 0117 982 3282 if you have any further questions about treating woodworm. 

Read more in How to Restore Woodworm-Infested Antique Furniture.