Woodworm

Woodworm tends to be used as a generic description for any attack by wood boring insects, but there are three types of insect that commonly cause this type of damage:

• Common Furniture Beetles;
• Death Watch Beetles; 
• Wood Boring Beetles.

Technically, woodworm is an odd description because the damage to timber is caused by the grub of the beetles and not a worm.  These grubs form tunnels below the surface of the timber. The holes visible in the wood are made by adult insects emerging in spring following pupation of the larvae into beetles.

This is an adult Death Watch beetle.  They are usually about 6-9mm long and have a similar appearance to Common Furniture beetles.

This is an adult Common Furniture beetle. They are smaller than Death Watch beetles, at around 3-5mm long.  If you look closely you can see that the wings are protruding from the bottom of its wing casings. This shows that this beetle has flown.  Common Furniture beetles are good flyers, but not all adults choose to fly.

Here are four adult Wood Boring weevils. These beetles are about 3-5mm long. A characteristic of all weevils is their long snout. This makes identification of Wood Boring weevils straightforward and distinguishes them from Common Furniture beetles, which are a similar size.

Although related, Common Furniture and Death Watch beetles differ in their attack. Death Watch beetles usually infest hardwoods that are affected by fungal decay, while Common Furniture beetles will attack any timber. This distinction is important because treatment of Death Watch beetle is also likely to require the removal of damp and decay.

This Common Furniture beetle infestation in the floorboards is old and inactive.  The tunnels formed by the grubs of the beetle have become exposed as the surface of the wood has been abraded.

This Common Furniture beetle damage is in the foot of a rafter.  The insects often cause considerable damage to the soft, outer sapwood parts of the timber while leaving the harder internal heartwood relatively unaffected.

This active Common Furniture beetle infestation affects the underside of the floorboards and was discovered when the floor was opened up.  The bore dust, which is called frass, is produced by the grubs of the beetles. The frass falls out of the bore holes and can be seen here caught in the cobwebs. Frass is helpful in identifying active attack.

Active woodworm, if left untreated, can cause severe structural damage.  Here, in this house built in the mid 1970s, the floorboards have collapsed because of Common Furniture beetle attack.  The unsound timbers were removed and replaced and the remaining floor timbers treated with insecticide.

These damp floor joists were targeted by Death Watch beetles.

Wood Boring weevils are about the same size as Common Furniture beetles but can be distinguished by their long snout – a feature common to all species of weevils.  Like Death Watch beetles, Wood Boring weevils thrive in decaying wood, and are often found where decay is present.  Primary treatment typically involves the removal of decayed timber.

Because Wood Boring weevils attack decaying timber, they can be particularly damaging.  The holes formed by weevils are ragged and uneven in shape--in contrast to Common Furniture beetle holes which are perfectly round-- and the tunnels often break through the wood surface.

Wood Boring weevil infestation of floor joists.

Britannia Preservation use timber preservatives sparingly. We place our emphasis on correctly identifying the nature of insect infestation and in establishing if an attack is active.  It is surprising how often woodworm attack is quite old, inactive, and does not require treatment.  Where treatment is required, Britannia Preservation's expertise ensures that the correct remedy is applied and the use of timber preservatives is kept to a minimum.