The beetles themselves are rarely seen. What you find is the evidence: small holes in a floorboard, a beam or a cupboard leg, and a little heap of powder that wasn't there last week.
Wood borer beetles lay their eggs in cracks and pores in timber. The larvae hatch and tunnel through the wood for months or years, eating as they go, then pupate just under the surface and chew their way out as adult beetles, leaving an exit hole. Then they mate and lay eggs in the same wood, or nearby, and the cycle starts again. The holes you see are where adults left. The damage that matters is the network of tunnels inside.
Three beetles cause most of the damage in Garden Route homes, and each has its own habits.
European house borer
The most serious of the three. Its larvae feed in softwood, especially pine roof timbers, trusses and battens, and they can spend several years inside a piece of timber before emerging. The exit holes are oval and fairly large, several millimetres across, and there may be very few of them even when the damage inside is extensive. Bore dust, if you see it, is packed in the tunnels rather than falling out. Because it attacks structural timber, it's the reason beetle certificates exist in the Western Cape, and it's the main beetle a beetle certificate inspection looks for.
Common furniture beetle
Small, round exit holes, around a millimetre or two across, in pine floors, older furniture, skirting boards, picture frames and plywood. A fine, gritty powder falls out of active holes. It's the beetle behind most "woodworm" in antique cupboards and old yellowwood or pine floors, and it's common in older homes in Knysna and the forest areas where there's a lot of old timber.
Powderpost beetles
These go after hardwoods with a high starch content, especially the sapwood near the bark. They reduce timber to a very fine, flour-like powder and leave tiny round holes. You find them in hardwood flooring, door frames, furniture, and imported hardwood items like bowls, carvings and baskets. New furniture or timber is often where they start.
Is it active or old?
That's the first question we answer, because many older houses have holes that have been there for decades. Signs of an active infestation:
- Fresh, pale powder below the holes, especially if it comes back after you've cleaned it up
- Holes with clean, bright edges, rather than dark and dirty ones
- New holes appearing in timber you know was clean
- Adult beetles on windowsills in late spring and summer, when they emerge
Old holes with dark edges and no fresh dust usually mean the beetles finished long ago. They don't need treatment, though the timber may still need checking for strength.
Why it matters
A few holes in a cupboard leg are cosmetic. Larvae in roof timbers or floor joists are structural, because the timber is hollowed out from inside and loses strength. A badly affected roof truss or floor joist may have to be replaced, and that's a builder's job as well as ours.
What you can do
- Check second-hand furniture before it comes into the house. Fresh dust and clean holes mean live beetles
- Keep roof spaces ventilated and dry, because damp timber is more attractive to some species
- Clean up the dust and watch the spot. If it comes back, call us
Treatment
Treatment depends on the beetle, the timber and how far it's spread: surface treatment of exposed timber, injection of active holes in thicker pieces, and separate treatment of badly affected furniture. Our wood borer treatment page explains it in detail, with local pages for Knysna and Wilderness. Phone 044 012 5011.
Selling a house? Our guide to beetle certificates when selling a house explains what the inspection covers and how to avoid delays.
Frequently asked questions
How do I know if wood borer is still active?
Look for fresh, pale powder under the holes that comes back after you clean it, holes with clean bright edges, and new holes appearing. Dark, dirty holes with no fresh dust are usually old.
What is the European house borer?
A beetle whose larvae live for years inside softwood roof timbers, leaving large oval exit holes. It's the main reason beetle certificates are required when houses are sold in the Western Cape.
Can wood borer spread from furniture to my floors?
Yes. Adults emerging from an infested cupboard can lay eggs in nearby timber, which is why infested furniture should be treated or kept away from the house.
Do old wood borer holes need treating?
Not if the infestation is no longer active. The timber may still need to be checked for strength if the damage is extensive.
When do wood borer beetles come out?
Mostly in late spring and summer, when adults emerge from the wood to mate. Beetles on windowsills at that time of year are a useful clue.