How to stop borer eating your home

Protect your largest investment.

There are up to seven species of wood-boring insect in New Zealand that might attack the timbers of your home or other buildings. The most common of these is the common house borer (Anobium punctatum) also known as woodworm in other parts of the world. A close relative is the native house borer (Leanobium flavomaculatum) is rarely distinguished from the common borer and may be the more common.

The life cycles of these insects are similar. Adult females lay up to 100 eggs on bare timber or in old flight holes. The eggs hatch after 4-5 weeks and the larvae bore through the wood, eating it and using yeasts in their stomachs to help break down cellulose in the wood. After 3-4 years the larvae will pupate in a chamber near the surface, then 4-8 weeks later the adult exits the wood by eating its way to the surface creating a ‘flight hole’. It mates and begins the life cycle over again. The flight holes are approximately 2mm in diameter for common borer and 3-4mm for native borer.

It is important that a thorough survey is carried out to ascertain the extent of any infestation. It is frequently the case that a few flight holes are visible on the exterior of painted weatherboards, however when the boards are examined more closely the interior of the timbers are badly damaged and many flight holes are present on the interior surface.

Treatment

Treatment of timbers to remove borer infestation is the same for whichever species is present.

Treat any bare wood with Kiwicare NO Borer fluid. This insecticide will penetrate deep into the timber and will kill larvae as they eat the wood and prevent adults from laying eggs on the surface. In normal circumstances, this will protect the wood for many years.

Inject flight holes with Kiwicare NO Borer Injection fluid. This comes in a handy aerosol supplied with a nozzle for fitting into the holes. The aerosol forces insecticide into the labyrinth created by the borer larva killing any larva in the labyrinth or nearby. It also prevents adult beetles from laying eggs in the flight hole.

During each flight season (October-May) set off Kiwicare NO Borer Borafume Bombs in roof voids and sub-floor areas. These knock down adult beetles that would lay eggs on the exposed timbers here and give protection to the surface of the timbers.

Borer prefers timber that has some moisture in it. Ensure that your sub-floor is dry and well ventilated. Check for plumbing leaks and unblock all air vents. Check for leaks in the roof and if you have old terracotta or concrete tiles check that they are well sealed. These can act like sponges soaking up water and increasing the relative humidity of roof voids. Kiwicare produces a silicone terracotta sealant called NO Leaks that can be used to seal tiles and walls.

This combination of treatment will protect your home and your investment.