Borer treatment in Auckland

Borer prefer seasoned or moist, untreated timber, which makes older Auckland homes a natural target - especially in damp areas, on the south side of a building, and in floor timbers that hold moisture. By the time you notice the flight holes, the larvae have usually been working inside the wood for years.

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How do I know it's active?

Look for frass - fine, gritty, orange-ish dust around small holes. Frass means borer are working in there now.

Is it dangerous?

Not to people. Borer don't bite or carry disease. They weaken structural timber over time, which is the real cost.

How long does treatment last?

Ten years or more in normal conditions. We use borate powders that diffuse into the wood and don't break down.

How to tell if you’ve got borer

The giveaway is frass - the powdery waste borer push out as they tunnel. It looks like fine sawdust with a yellow or orange cast and feels slightly gritty between your fingers. Frass around a hole means borer are working in there now, not years ago.

What to look for

Small piles of frass - fine, gritty, yellow-orange dust
Frass trailing down from holes in the timber
Frass settling on things stored in the affected area
Small round or oval flight holes in the timber
In bad cases, visible damage to the structure of the wood

It’s completely normal for borer to attack some boards and leave the ones beside them alone - the untouched ones are usually harder heartwood. Borer prefer soft sapwood and untreated timber, which is why untreated native timbers in older homes are so often affected, and sawn timber more than smooth-finished.

Flight holes left by wood-boring beetles in a timber surface

Flight holes in timber

Badly damaged subfloor timber, with bearers and joists broken down

What untreated timber damage ends up looking like

Why a hole means it’s already old

Almost the whole life cycle happens inside the timber. The hole you can see is the exit - made by an adult on its way out, years after the damage started.

1
Eggs laid
Females lay up to 100 eggs on bare timber or inside old flight holes.
4-5 weeks to hatch
2
Larvae burrow in
They tunnel into the wood and eat it, using yeasts in their stomachs to break down cellulose.
3-5 years inside the timber
3
Pupation
The larva forms a pupa in a chamber close to the surface.
4-8 weeks
4
Adult emerges
It eats its way out - leaving the hole you can see - then flies October to March, mates, and starts again.
The hole appears here

Hole size tells you the species. About 2mm across is Common House Borer, 3 - 4mm is Native House Borer, and up to 7mm and oval is Two-Toothed Longhorn Borer.

How we treat it

Which treatment you need depends on the timber. Bare wood takes a preservative that soaks in; finished wood has to be treated through the holes themselves.

Most common

Bare timber

Framing, subfloor, roof space, untreated native timber

MycroBor & Pest-Bor

Water-soluble borate powders applied to the surface. They diffuse right into the wood rather than sitting on top of it, and act as insecticide, fungicide and preservative at once.

Protection: 10+ years in normal conditions
Resistance: None known - almost pure sodium borate
Smell: Odourless once applied

Finished surfaces

Painted or varnished wood

Skirtings, joinery, floorboards, furniture

Residual pyrethroid

Borates can't penetrate a sealed surface, so we pressure-inject insecticide directly into the flight holes instead - reaching the tunnels where the larvae actually are.

Applied by: Pressure injection into flight holes
Suits: Furniture and finished joinery
Finish: No stripping or sanding needed

Why longevity is the whole point. A borer larva can sit inside timber for three to five years. Any treatment that breaks down faster than that just clears one generation and waits for the next - which is why we use a preservative that outlasts the life cycle rather than something that kills whatever happens to be near the surface today.

It might not be borer

Three different insects attack building timber in New Zealand, they leave similar-looking damage, and they don’t all need the same treatment. That’s why we identify what’s actually in the wood before anything gets applied.

House borer

Round holes about 2mm across

The most common by a distance. Fine orange-ish frass around small round flight holes.

Flight holes in timber, showing the size difference used to tell species apart

Two-toothed longhorn

Oval holes up to 7mm

A different beetle leaving similar damage. Larger, oval holes - easy to mistake for a bad borer problem.

New Zealand drywood termite, Kalotermes brouni

NZ drywood termite

Few holes, hard to spot

Yes, New Zealand has termites. They live in the same damp conditions as borer larvae, so they're rarely the only cause of damage - and because exit holes are few and hard to see, it can spread a long way before anyone notices.

Buildings closely surrounded by neglected shelter trees tend to be worse for all three. More on termites in New Zealand.

Qualified, accredited and accountable

National Pest Management Association

Pest Management Association of NZ

Site Safe member

Borer treatment - common questions

How can I tell if I have an active borer problem?

Look for small holes in the timber, and for frass - the powdery waste borer push out as they tunnel. It looks like fine sawdust with a yellow or orange colour and feels slightly gritty between your fingers. Frass around holes usually means borer are actively working. Look for small piles of it, frass trailing down from holes, and frass settling on things stored in the affected area.

Are borer dangerous to people?

No. Borer do not harm humans. What they do is weaken timber, and over enough time that can threaten the structural strength of a house or building. That is why treatment matters - not because the insect is a health risk, but because the damage is cumulative and does not reverse.

How long does borer treatment last?

We use MycroBor and Pest-Bor on bare timber - water-soluble borate powders that diffuse into the wood and act as insecticide, fungicide and preservative. Unlike most organic compounds they do not break down over time, so in normal conditions the treatment prevents borer reappearing for at least ten years. There is no known pest resistance to it.

Can I treat borer myself?

Do-it-yourself methods for wood-destroying insects often don't work. It takes a trained eye to know where and how to treat - which timbers are affected, which are heartwood and were never at risk, and whether the damage is borer at all rather than longhorn beetle or drywood termite. Treating the wrong timber with the wrong product is a common and expensive mistake.

Why do some boards get attacked and others don't?

It is completely normal for borer to attack some boards and leave the ones beside them alone. The untouched boards are usually harder heartwood. Borer prefer soft sapwood and untreated timber, which is why older homes with untreated native timbers are the most affected.

Where in a house is borer most common?

Damp, shaded areas. The south side of a building and floor timbers are classic spots, because they hold moisture. Sawn timber is more vulnerable than smooth-finished timber - the rough surface gives easier access. Buildings closely surrounded by neglected shelter trees tend to be worse.

Think you've got borer?

We'll identify what's actually in the timber before anything gets treated.