Wood-destroying insects are beetles and larvae that feed on wood and bore galleries into it, weakening the wood from the inside. Together with fungi (wood rot) they form the most important type of biological wood decay in buildings. Most of the damage is done by the larvae, not by the adult beetle.
Common wood insects
- Common woodworm — the larva of the furniture beetle; leaves small round exit holes (about 1 to 2 mm) and fine bore dust. Mainly in damper wood
- House longhorn beetle — large larvae that mainly attack softwood and cause substantial oval holes and heavy damage; can seriously weaken structural timber
- Wood wasp and powderpost beetle — attack specific wood species or the sapwood
How do you recognise infestation?
- Exit holes — round or oval holes in the wood surface
- Bore dust — small heaps of fine powder (frass) under or next to the wood
- Soft or hollow-sounding wood — an awl sinks in easily when probing
- Gnawing sounds — with the longhorn beetle sometimes audible in quiet rooms
Application and treatment
- Remove moisture — many wood insects thrive at a higher moisture content; ventilating and tackling moisture sources is the basis
- Treatment — treating with a wood preservative (insecticide) or, in case of severe infestation, a specialised treatment
- Affected structural timber — for load-bearing parts (beams, trusses) always have the strength assessed; severely affected wood must be strengthened or replaced
- Prevention — use preserved or naturally durable wood and keep it dry
Point to note
Distinguish active from old, inactive infestation: clean, light holes with fresh bore dust indicate active activity.
Related terms
- Wood rot
- Wood
- Wood joints
- Ventilation
- Building moisture
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