Woodworm arrives in many forms, its damage ranging from superficial to structurally weakening.

 

Although the UK is rich in its beetle types, only a small number are wood-boring, and cause problems in homes.

 

The most usually found, Common Furniture Beetle (anobium punctatum) is frequently seen in floor boards, and often in the timber surrounding the loft hatch. They are also found in furniture, hence the name!

 

Some occupiers of terraced houses worry that their treated floorboards will be come re-infested from them crawling back in from next door. Woodworm are not contagious as such, but they can fly in, like any insect, to your home. However, they can only successfully lay eggs if they find an adequate host, i.e. an undisturbed piece of timber with a suitable moisture content. Some beetle types require the timber to have already been softened by wet or dry rot.

 

 

As beetles do not drink, any moisture they take has to come from the timber they eat, hence their presence usually indicates a dampness problem to some degree. Timber with a constant moisture content of below 14% is not capable of supporting insect development – the installation of central heating has sometimes been enough to eradicate an attack!

 

The adult female lays the eggs on the surface or in cracks in the wood. These eggs hatch in to larvae (grubs) which then feed on the timber, staying just under the surface, or going deep, dependant on their type, causing weakening of the internal timber which is not apparent upon a visual inspection. The larvae pupate, for a length of time dependant upon their type, from as little as one year for Common Furniture Beetle, to up to several years for Death Watch Beetle. When the adult beetle emerges from the pupae, the damage caused by its eating out to the surface (emergence or flight holes) is often the first symptoms that an infestation is present.

 

 

 

It is difficult for the untrained eye to tell whether an infestation is live or defunct. One way is by inspecting the exit holes – are they clean and pale? Old flight holes may have become darker. Additionally, loose dust is usually present in active attacks.

 

Unfortunately, the adult beetles very rarely die right next to their exit holes to give a body for the surveyor to easily identify. Instead we have to resort to other methods.

 

The dust which can be collected from the underside of the affected timbers can also give clues. If you are able to tell if there is significantly more dust at certain times of the year, this may help determine which insect is present.

 

This dust (frass) is what’s left after the beetle has eaten its way out to the surface. It’s bits of munched timber, and beetle poo! The poo is important, as each beetle type produces different shapes, and it can be a handy identification tool.

 

It is important to identify your beetle. There’s no point in treating your attack with an insecticide if the beetle is rot-dependant (see list below). With these, if the wet or dry rot is addressed, the insect infestation will also be eradicated. Sole insecticidal treatment may be short term and may not result in long term removal.

 

 

Similarly, some beetles affect only standing trees, newly cut timber, or cut but ‘green’ sawn timber (includes powderpost beetle, and pinhole borer), and thus will be in-situ before the timber has even reached the merchant. This type of beetle will die as the wood dries out in use, but some emergence holes will occur, and can cause grief in homes where expensive imported wood is affected, such as bamboo.

 

Beetles that live

 

 

Insecticides carried in a fluid, paste or gel can be applied by brush or spray, in a water, solvent or glycol carrier. Penetrating the timber they can act in several ways, some killing the larvae, some causing the timber to become toxic (to insects), and some which work by affecting the successful development of the adult beetle.

 

Insecticides absorbed in this way are quite stable, and will remain in the timbers for many years, protecting from future attacks. It should be noted that allowing the timber to become damp, through leaks etc., may dilute the active ingredient and put the timbers at risk again. Guarantees will not protect against this!

 

If an annual treatment is acceptable, ‘smoke’ treatments can be used. These kill all emerged adults in the vicinity and leave a toxic residue for newly emerged in the near future. Although very useful if the area to be treated is difficult to physically access for spraying, such as small lofts or sub-floor voids, the timber is left unprotected form the next season’s new arrivals.

 

 

Again, it all comes down to maintenance. Check the roof for slipped tiles or slates, make sure all ran water goods run freely, and keep air bricks clear.