Timber pests

Borer or termites?

Borer and termites both hollow out timber, but the dust, the holes and the next step differ. How to tell them apart in a New Zealand house, and when to call MPI.

The short answer

In a New Zealand house it is almost always borer. Borer leaves small round or oval exit holes and soft or gritty dust, while termites leave no rows of exit holes and push out hard, six-sided pellets, or build mud tubes. Borer is a timber problem for borer treatment. Anything that looks like termites in building timber or imported furniture is a biosecurity question first: leave it undisturbed and report it to MPI on 0800 80 99 66.

At a glance

Borer and termite evidence side by side

Borer and termite evidence side by side
Sign	Borer	Termites
Holes in the surface	Many, round or oval, 1–7 mm depending on the beetle	Very few and inconspicuous; the surface usually stays intact
What comes out	Bore dust, gritty or talc-fine, sometimes packed	Hard pellets, rounded at each end, six-sided in cross-section
Where the damage is	Visible holes, tunnels mainly in sapwood	Hollowed from inside, galleries along the grain
Flying stage	Small beetles, mainly November to January for house borer	Winged termites swarming in late summer or autumn
Mud tubes on piles or foundations	Never	Report to MPI at once

How do you tell borer damage from termite damage?

Look at what comes out of the wood. Borer pushes bore dust out through visible round or oval exit holes, gritty for the common house borer (Anobium punctatum) and talc-fine for the powderpost beetle. The native drywood termite pushes out hard pellets, elongated, rounded at each end and six-sided in cross-section, through a few inconspicuous openings, and leaves the surface of the timber intact. Mud tubes on piles or foundations are never borer.

The rest follows from that. Borer announces itself, because the holes are on the surface where you can see them, and the adults of the common house borer emerge mainly from November to January. Termites hollow timber from inside along the grain, so the Scion leaflet on the native drywood termite warns that its damage can go unnoticed for a long time. Their flying stage is a swarm of winged termites, about 5 mm long with wings reaching about as far again, in late summer or autumn.

Which is worse, termites or borer?

In New Zealand, borer does far more damage overall. The common house borer is responsible for most of the insect damage in structural and decorative timber here, while our native termites are small, mostly live in dead wood outdoors, and the wetwood species are rated of little economic importance. The termites that would be worse, Australian subterranean species, are not established here and have been eradicated whenever they have been found.

So the comparisons that fill search results, most of them written for Australian or American houses where subterranean termites are a routine threat, do not describe the risk to an Auckland villa. An established borer infestation in a subfloor is a real repair bill. An exotic termite find is rare, but it is a national biosecurity matter, handled by MPI rather than by a private company, and that difference shapes what you should do first.

What to do if you think it is termites

Do not spray it, do not break the timber open further, and do not move or throw out the affected wood or furniture. Photograph the insects, pellets, tubes or wings, note exactly where they are, and call MPI's Exotic Pest and Disease Hotline on 0800 80 99 66. Several exotic termites are notifiable organisms, so anyone who finds one is legally required to tell MPI, and spraying can scatter a colony MPI needs to find.

This applies to drywood termites too, not only to subterranean ones. The exotic drywood termites found in New Zealand have arrived in imported timber and furniture, and their pellets and wings look much like those of our native species, so termite activity in building timber, imported furniture or anything brought in from overseas is reported first and identified afterwards.

What we can do is tell you, from photographs or on site, whether you are looking at borer, a native termite in rotting outdoor wood, or something to report, and help you make that report. We never treat a suspected exotic termite privately. Our guide to which termites live in New Zealand covers the native and introduced species, and termite identification and control sets out what we can and cannot do.

Can borer and termites be in the same timber?

They can, because they like the same conditions: untreated timber, and damp, poorly ventilated subfloors. Scion notes that the conditions that suit the native drywood termite in buildings also suit the two-toothed longhorn and the common house borer, so it is rare for termites to be the only thing at work. Native wetwood termites and huhu grubs both turn up in rotting wood as well.

So finding one is a reason to look hard at the moisture and condition of that timber generally, rather than proof of the other. Fix the moisture first, because both depend on it. Preservative-treated framing resists both, which goes a long way to explaining why newer houses rarely see either, and why the damage we find is so often in original untreated timber.

Questions

Questions about borer and termites

Do termites leave holes like borer?

No. Drywood termites stay sealed inside the timber, using only a few small, inconspicuous openings to push out pellets and to let the winged adults fly, so the damage is hollowing from within rather than a surface peppered with holes. If you are looking at many small round holes with dust in or below them, you are almost certainly looking at borer.

Are there termites in Auckland?

Native termites live in dead and damp wood throughout New Zealand, Auckland included, and three introduced species have become established, none of them of great economic significance. Australian subterranean termites are another matter: they turned up at several Auckland sites, among them Coatesville, Pukekohe, Point Wells and Drury, and official programmes eradicated them each time.

Will borer treatment kill termites?

Do not rely on it, and do not try. A borer product on bare timber is not a termite treatment, and with a suspected exotic termite any spraying is the wrong first step, because it can drive the colony deeper or scatter it. Identify first, and report anything termite-like in building timber or imported furniture to MPI before anyone treats anything.