LTP Newsletter - February 2009- Issue No.16

Wood Worm: Beware - it’s that time of the year.

woodworm

Did you know that most of the year round the woodworm is happily munching away in timber and in spring they emerge?

Woodworm is a lava grub which comes from a egg and bores its way into timber and continues to eat until it nears adulthood, then the little maggots evolve into a small flies. They emerge to continue their cycle of destruction where they fly further afield to lay more eggs in untreated timbers. These invasions takes place from May to June each year.

In the UK and Ireland, the most common are the Common Furniture Beetle (Anobium punctatum), Deathwatch Beetle (Xestobium rufuvillosum), House Longhorn Beetle (Hylotrupes bajulus) and Powderpost Beetle (Lyctus brunneus). All invade and consume wood, and then leave when they have reached maturity

Wood worm thrives in damp conditions, a moisture content of 20% would be a cause for concern. Woodworm prefers timber with moisture content over 18 %, although it can tolerate moisture contents as low as 12 % for short periods. At lower moisture levels however, the rate of colonisation tends to be low and infestation will die out with prolonged periods of reduced moisture levels.

Ways to reduce the risk of woodworm spreading:

Keep humidity levels low and ensuring wood is well-ventilated.

Remove pieces of furniture or non-structural timber that are infested to avoid the woodworm spreading.

Install electric fly traps in attic/ loft spaces and under-ventilated areas to kill the adults during the emerging months, and thus reduce the threat of infestation.

Surface application of pesticides /treatment with wood worm killer such as Protrim.

Freezing – only suitable for items of furniture infested with woodworm.

Fumigation – usually appropriate for Deathwatch Beetle infestation in large structural hardwoods. The adult beetles are effectively "smoked out" during the annual flight season.
Environmental concerns

While it is tempting to opt for a blanket treatment, this may not be the greenest choice. It is worth bearing in mind for example, that treated timber is considered toxic waste at the end of its lifespan and must be disposed of accordingly.
A safe but effective treatment is borax, a compound of boron also known as sodium borate. This is available as a crystalline powder, which is dissolved as a 15% solution in water and applied to the affected timber. There are no health hazards associated with this treatment, and borax will inhibit fungal growth as well as killing woodworm.
You won’t know you have killed him until next year if you see no fresh holes appear.

The amount of harm caused by woodworm will depend on the species of beetle and the type of wood -

Common Furniture Beetle Attacks softwood (conifer) and the sapwood of European hardwoods. Rarely causes structural weakening although tunneling along the grain of the wood can potentially cause extensive collapse.

House Longhorn Beetle Only attacks the sapwood of softwood timbers. As softwood is often used in roof timbers, infestation can often result in severe structural weakening. The good news is that this species is now rare in the UK.

Powderpost Beetle Causes damage to wide-pored hardwood with a high starch content, such as ash, elm and oak. Older timbers (over 15 years old) don't provide a suitable environment for this species. Tunnels along the grain and can cause severe damage, often infesting block or parquet flooring.

Deathwatch Beetle Prefers European hardwoods, especially oak, ash and chestnut that has been "softened" by partial decay. The larvae tend to tunnel towards the centre of the timber, so that damage may be more extensive than is apparent from the exterior. In the UK, this species is concentrated chiefly in southern/central England, and is virtually absent in Scotland.

So be warned, if you have any untreated timbers or furniture that you have been meaning to “get round to finishing”, oil it, paint it or treat it now!

Did you know that spiders are the only natural killers of woodworm!