Woodworm: signs, active or historic, and treatment

What is woodworm?

Woodworm is a term used for the larvae of wood-boring beetles. They can cause significant damage to wooden structures and furniture, often going unnoticed until the damage is done.

Several species of wood-boring beetle live in the UK, but the most common is the Common Furniture Beetle (Anobium punctatum).

What are the signs of woodworm?

Early detection saves trouble and expense. The most common signs are:

• Small round holes in woodwork, similar in size to the holes in a dartboard
• Fine, powdery dust around the holes, known as frass
• Crumbling wood at the corners or edges of roof joists or floorboards
• Adult beetles emerging from the holes or present around the house

Is the woodworm active or historic?

Fresh frass usually indicates an active infestation. A lack of frass, or old, darkened holes with no signs of recent activity, typically indicates a historic one.

The difference matters. An active infestation needs immediate attention and treatment. A historic infestation is no longer active, but it may have caused damage.

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Which properties are at risk?

Any property containing untreated wood can be infested. Older properties are particularly at risk because they often contain more untreated timber. New properties are not immune, especially if they contain reclaimed or recycled wood.

What to look for when viewing

• Small round holes in floorboards, roof joists and other timber
• Fine, powdery frass around or beneath holes
• Crumbling edges or corners on joists and floorboards
• Adult beetles around the house
• Damp timber or leaks, especially in the attic and basement
• Reclaimed or recycled wood in newer properties

How is woodworm treated?

The right treatment depends on the species of beetle and the extent of the infestation.

• Minor infestations: DIY products such as woodworm killer sprays or paints can be effective.
• Severe or inaccessible infestations: professional treatment is recommended. This often involves insecticides sprayed or injected into the wood.
• Badly damaged timber: treatment may involve replacing the affected wood.

Treatments can kill the larvae and help prevent further infestation, but they cannot reverse damage already done.

What to do next

1. Identify: confirm there is a woodworm problem by looking for the signs above.
2. Assess: establish the extent of the infestation and the damage caused. This may need professional help.
3. Treat: depending on severity, use sprays or other insecticide treatment, or replace the affected wood.

How can woodworm be prevented?

• Inspect the property regularly for signs of woodworm.
• Treat any untreated wood with a wood preservative.
• Keep the property dry. Wood-boring beetles are attracted to damp wood, so reducing humidity and fixing leaks helps prevent infestation.

What a survey can — and cannot — tell you

A building survey provides an informed assessment of the visible condition of a property. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.

A surveyor can look for the visible signs of woodworm and note evidence that suggests whether an infestation is active or historic.

• Small round holes in accessible timbers, such as roof joists and floorboards
• Frass around or beneath holes
• Crumbling timber at corners and edges
• Damp conditions or leaks that make timber attractive to beetles

However, there are limitations to what a survey can determine without intrusive investigation.

• Timber hidden beneath floor coverings, behind linings or in inaccessible areas
• The full extent of damage within affected timbers

Where higher-risk indicators are identified, further specialist or intrusive investigation may be recommended.