How to stop woodworm from ruining your pieces

Do not fear — even the worst cases of woodworm in furniture can be treated.

NOT many of us have a full understanding of the ageing process on a piece of elderly furniture. Kept in overheated or humid conditions, moved from one environment to another, the occasional berth in an outbuilding when it falls from stylistic favour — it all puts stress on the joints.

Still, one thing we all recognise without prompting is woodworm. The larvae we erroneously term as worms are larvae of the Anobium punctatum or common furniture beetle. They rely on safe, nutritious surrounds to thrive and the female beetle is on the hunt for a softwood crib from May to September. Left untreated for decades in the right conditions, they can destroy the structural integrity and looks of a nice piece.

Natives of the forest floor, the larvae of Anobium love the top layer of the tree — the sapwood. A piece of walnut, pine or beech furniture with a moisture content of 16-18% in a damp old house provides at least tolerable cover to lay their eggs. The female beetles are picky divas and will turn up their antennae at solid hardwoods such as mahogany which would be too tough for their infants to penetrate. Erupting wood beetle larvae are known to enjoy a spot of animal glue, typically used to hold down antique veneers and marry joints. Sloughing off that tender, interrupting layer as a first course, they wend their merry way into the yielding main course. The larvae then gorge themselves on the probably already failing wood, passing the faeces we spot as dust. Woodworm are late bloomers reaching their adult stage after 3-5 years when they finally flutter off towards the light. Boring out, the adult winged beetles creates those tell-tale holes of 1-2mm in the furniture’s surface.

Unfinished bottoms and backboards without any protective layer of lacquer or wax are often the first place we notice the tiny lodgers. In May/June when they are at their most active, the signs are not difficult to detect. If you have the eyes of a watchmaker you might even spot the minute pearly eggs in a crack or crevice of old wood. If you give the area a light bang and dusty material appears, the larvae may be still active. If you do spot the holes anywhere on a piece you own, or are considering, don’t lose the plot. The holes may be 10 years or a century old.

A modern home with controlled ventilation, heating and insulation is actually not a good environment for Anobium. Moved from an auction floor to a warm centrally heated house with 10% humidity (they favour 28%), the rotters will soon be gasping for some sweet hazel wood out in the garden. As the larvae have a lifespan of 3-5 years, once dealt with and moved to a dry setting, your furniture will probably not be troubled again, and there’s little chance of them jetting off into the treated timbers of the rest of house. Where beetles are active, they are sometimes spotted trying to fly the nest, gathering around the insides of window panes from April to August. Lovely.

To treat woodworm, there are a number of proprietary oil based solutions you can inject, spray or brush over the infected area, to run poisonous chemistry into the flight holes and bore canals. Any DIY store can recommend a product. Check the underside of chairs and tables and inside drawers and do a patch test with the chemical for highly visible areas without a hard finish. This is generally a high VOC experience, best performed outside on a well ventilated outbuilding. This also provides more room to turn the piece and allow the fluid to flow into the flight holes as you work. If the plywood backboard of a lesser piece is heavily damaged, it’s probably worth replacing.

If the item is reasonably valuable, or has hidden timbers under old upholstery, put it in the hands of a restoration professional, ensuring they know the issue before removing it to their premises.

For larger items, such as tables and dressers, a gassing procedure can smother and kill the larvae in a single treatment without wetting andstaining valuable wood. If you have patience and a suspected infestation is confined to a single area, Rentokil recommend filling the flight holes with furniture wax after treatment, such as a beeswax mixture. Ensure you know where the spot was, and take note of any signs of new holes or escape over the course of a year.


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