Small round holes in timber, often with a little pile of dust underneath, are the mark of borers, not termites. Borers are beetles whose grubs feed inside the wood and chew their way out as adults. Subterranean termites work out of sight and cover their tracks with mud. The NSW Government's heritage sheet on wood preservation says most borer damage is minor and rarely needs treating, but some borers cause serious damage, and knowing which one you have can save an unnecessary treatment.
What makes the holes?
Most borers follow the same life cycle. Eggs are laid in cracks or pores in the timber, the grubs hatch and tunnel through the wood for months or years, and the adult beetles bore out through a round exit hole and fly off to breed. Those exit holes, and the fine dust called frass that falls out of them, are usually the first sign anything was there.
That means every hole you can see is a beetle that has already left. The NSW EPA's page on timber pests notes that lyctid grubs can live inside the wood for over a year before the adults come out through small shot holes, sometimes leaving dust on the surfaces below.
The heritage sheet sets out three questions to answer once you find borer holes: is the borer still active, which type of borer made them, and how far does the damage go?
Which borer is it?
The heritage sheet describes several borers found in Australian building timbers. These three are the ones most worth telling apart.
- Powderpost beetles (lyctids) attack only the sapwood of certain hardwoods. Their dust is very fine and powdery, like flour, and stays packed in the tunnels. NSW law limits how much sapwood can go into framing timber, so they usually do little structural damage even when the sapwood is riddled.
- Furniture beetles (anobiids) attack the sapwood of softwoods, especially old, well seasoned timber such as Baltic pine. Their dust feels gritty, like fine salt. Business Queensland's common furniture beetle page describes 1 to 2 mm exit holes, tunnels that leave the wood honeycombed, and attacks that are heaviest in damp spots such as flooring and skirting boards.
- Pinhole borers attack green logs and standing trees and die out as the timber dries. Their tunnels often have a dark stain, and the damage was done before the timber was ever used, so no action is needed.
The heritage sheet calls furniture beetles a hazard to old buildings and says active infestations must be treated. They prefer damp, humid conditions such as poorly ventilated floors.
Gymea saw substantial development after the Second World War. A Gymea owner who lifts a rug in a back bedroom and finds rows of pinprick holes with gritty dust along the pine boards should book property pest inspections in Gymea to find out whether the beetles are still active and how deep the tunnels run.
Why are there holes in my new plasterboard?
Holes can also show up in walls rather than floors. Business Queensland's powderpost beetle page explains that in newer homes, exit holes can appear in plasterboard, panelling and joinery. The beetles grew in the hardwood framing behind the lining and chewed straight through it on the way out.
That page also says timber can be reinfested for up to five years after the tree was felled, until the starch in the sapwood runs out. So holes in fresh walls usually point to the framing timber, not something that came in from the garden.
A Bangor family whose new rumpus room starts showing tiny round holes in the plasterboard, with a fine powder on the skirting below, can arrange a quick property pest inspection in Bangor to confirm it is powderpost beetle in the frame and rule out anything more serious.
How is termite damage different?
Termites are the real threat. The heritage sheet says that, unlike borers, termites are a major hazard to timber buildings, and the NSW EPA says subterranean termites cause the most damage to timber in NSW.
Subterranean termites nest underground, often in old stumps and roots, and need dark, moist conditions such as a poorly ventilated subfloor. They can't survive long in open air, so they build mud shelter tubes up piers, stumps and the base of walls to reach timber. They eat the wood from the inside and leave the surface intact, which is why the heritage sheet says the first sign is often a floorboard that gives way.
So look for mud, not holes: mud tubes running up piers, stumps or brickwork, and floorboards that feel soft or give way underfoot. Drywood termites are the exception. They leave distinctive small pellets rather than mud, and the heritage sheet notes that the introduced West Indian drywood termite has been found in several places between Sydney and Brisbane.
Jannali began to grow when the railway arrived in 1884, and its streets now mix houses, units and reserves full of native plants and wildlife. A Jannali owner who finds borer holes in the hallway and dried mud along a subfloor pier should book termite and timber pest inspections in Jannali, because a house can have old borer damage and live termites at the same time.
Should you worry if you are buying?
Borer holes are usually less worrying than termite activity, but they still belong in a pre-purchase report. A timber pest inspection looks for termites, borers and wood decay together, and notes conditions such as damp subfloors that suit all three.
Cronulla is Sydney's southernmost coastal suburb. A buyer who notices pinholes along the floorboards of an older Cronulla house at the open inspection should arrange property pest inspections in Cronulla before exchange, so the report says which borer it is and whether anything is still active.
Don't sand, fill or varnish over the holes before an inspection. Fresh dust and new holes help show whether borers are still active, and covering them hides that evidence.
Before you book
Note these details so the inspector knows what to look for:
- where the holes are: floorboards, skirting, framing, furniture or new plasterboard
- what the dust is like: fine and floury, gritty like salt, or none at all
- whether new holes or fresh dust have appeared recently
- any mud tubes, soft timber or floorboards that sag
- the age of the house and any recent renovation work
Send those details when you contact us for pest control for older Sutherland Shire homes: call Sutherland Shire Pest Control Pro on 02 8360 3033 or email [email protected].