The Pest Advice

Borer beetle

• Identification
• Borer are also known as woodworm and furniture beetle.
• Species – Common Borer, Native Borer, Two-Tooth Borer, Citrus (Lemon Tree) Borer and others.
• Eat dead wood – dead trees, construction timber, furniture.
• Common Borer (and Native) adult beetles are small brown beetles (2-3mm) that can fly. Often found on windowsills.
• Small holes in timber – like drawing pin holes.
• Two-tooth – not so common – larger black beetle (6-7mm)
• Holes 4-5mm oval
• Dust falls out of holes.
• Clean wood inside hole means the hole is probably recent, meaning ongoing infestation.
• Holes tend to be in areas of low light – i.e. more under floor than on top.
• Breeding
• Female beetles lay eggs on bare timber i.e. not on paint, varnish, polish etc.
• But they will lay eggs in old flight holes.
• Eggs hatch as larvae that burrow into wood.
• After 2-4 years larvae pupate near surface.
• Adult beetle emerges and eats its way out – flight hole.
• Borer flight season October to March in NZ.

• Feeding habits
• Larvae eat wood – digest cellulose with micro-organisms in gut.
• Only eat soft timbers – sap wood.
• Hard heartwood usually un affected.
• Prefer wood with a little moisture – sub-floor, roof timbers near leaks, or with moisture holding terracotta/concrete tiles.
• Because of slow growth it takes many years to do significant damage to timbers.
• But many houses in New Zealand are over 50 years old.
• Spread
• Borer live in wild as well as in houses.
• Fly from house to house, forest to house, in furniture moved from house to house.

• Treatment
• Fluids
• Borer fluid on accessible timber – sub-floor, roof timbers, when GIB off internal walls etc.
• Fluid will not be effective on paint or other coatings.
• Borer Injector – flight holes.
• If many holes close together, possible to use NO Borer in sponge and sponge ito holes. (wipe off excess).
• Smell from solvent (turps or kerosene) can last several days. Only use in good ventilation.
• Spray or brush on. If spraying, use coarse spray to reduce mist in atmosphere.
• Fumigators
• Kiwicare NO Bugs Borafume or Bug Bomb
• Fumigators for places where timbers cannot be treated – hard to reach, painted areas, etc. Need to be used on 4+ consecutive years.
• Fumigate October to March (NZ).
• Borer fluid any time.

Are you finding more of those little holes in the wood around your home?

Spring sees the beginning of the borer flight season when the adult beetles emerge from their wooden food source to mate and start the cycle of destruction all over again. Homes in cooler and damper parts of New Zealand such Otago and Southland are most affected by these destructive insect pests but no part of the country is immune. Each year, as more damage is accumulated, our homes and other affected buildings become weaker.

It might take more than 50 years for damage to accumulate to the point of failure but the number of homes reaching such a venerable and vulnerable age is increasing. It is estimated that over six hundred thousand New Zealand homes are now over 50 years old.

Thankfully borer do not damage timbers as quickly as termites. If the slow increase in holes is noticed at all, the progress of the damage is often ignored for years. Each year the floor boards might creak a little more and the weatherboards might take a little more filling before painting; but until a floor board fails and you fall through, or the weatherboards start to rot because of water penetrating the holes, you may not be aware that your home is in danger.

Borer tend to attack softer timbers, so the older houses with structural timbers made of good quality heartwood are likely to be structurally safe, but even these houses often have decorative or non-structural timbers of softer sapwood. We often see weatherboards or floorboards riddled with borer holes next to undamaged boards. Even the same board may be heavily damaged in one area and undamaged elsewhere.

Floor board showing borer damage in lower two thirds

In the 1950s preservative timber treatment was introduced to new buildings and this has protected many timber homes of less than 60 years of age, but not all later houses used treated timbers and treatment loses effectiveness over time; it should not be expected the treatment will give protection for more than 50 years. There are many homes older than 50 years with susceptible timbers and the slow chewing of borer beetle larvae is now making more and more timbers fail. It might be too late for some parts of older houses but the borer damage can be stopped or at least slowed greatly by the use of protective borer products.

The larvae of the common wood boring beetles (Anobium punctatum and Leanobium flavomaculatum) are slow eaters; they chew through the interior of untreated timbers for 2-4 years before emerging from the wood between October and March. As they emerge they open the small (2-3mm) holes in the surface of the wood that we identify as borer infestation. When we see these holes in our weatherboards, architraves, skirting, floorboards and furniture we only see the ‘tip of the iceberg.’ The vast majority of the damage is within the timber where a labyrinth of tunnels has weakened the wood.
Borer control can be carried out effectively by the use of borer fluids that penetrate deep into the affected timbers and provide protection for many years. Even the timbers that are hard to reach such as roof timbers and floor timbers can be given protection by the use of borer bombs during the flight season. These kill the adult beetles that have emerged from the flight holes and stop them mating and laying their eggs back on the timbers. There are also aerosol injectors that can be used to treat individual flight holes in damaged painted or varnished wood. This will kill larvae deep within the wood and prevent eggs being laid in the holes.

Spring is a good time to examine your home for sign of borer infestation. I suggest looking for fresh flight holes. These will have a clean appearance inside the hole. It may take examining the holes with a magnifying lens. Sand like dust known as frass may also fall out of the flight holes when the wood is given a tap. So check your home and protect it from damage now before you fall through the floor.

A borer beetle walks into a bar. 
The bar says to the bartender. “I’m bored.”

In New Zealand our older housing stock is weakening each year as more wood boring beetle damage is accumulated. The larvae of the common wood boring beetles (Anobium punctatum and Leanobium flavomaculatum) are slow eaters; they chew through the interior of untreated timbers for 2-4 years before emerging from the wood between October and March. As they emerge they open the small (2-3mm) holes in the surface of the wood that we identify as borer or woodworm infestation. When we see these holes in our weatherboards, architraves, skirting, floorboards and furniture we only see the ‘tip of the iceberg.’ The vast majority of the damage is within the timber where a labyrinth of tunnels has weakened the wood.

Floor board showing majority of damage in lower half

Thankfully borer do not damage timbers as quickly as termites. If the slow increase in holes is noticed at all, the progress of the damage is often ignored for years. Each year the floor boards might creak a little more and the weatherboards might take a little more filling before painting; but until a floor board fails and you fall through, or the weatherboards start to rot because of water penetrating the borer holes, you may not be aware that your home is in danger.

It might take more than 50 years for damage to accumulate to the point of failure but the number of homes reaching such a venerable and vulnerable age is increasing. It is estimated that over six hundred thousand New Zealand homes are now over 50 years old.

Borer tend to attack softer timbers, so the older houses with structural timbers made of good quality heartwood are likely to be structurally safe, but even these houses often have decorative or non-structural timbers of softer sapwood. We often see weatherboards or floorboards riddled with borer holes next to undamaged boards. Even the same board may be heavily damaged in one area and undamaged elsewhere.

In the 1950s preservative timber treatment was introduced to new buildings and this has protected many timber homes of less than 60 years of age, but not all later houses used treated timbers and treatment loses effectiveness over time; it should not be expected the treatment will give protection for more than 50 years. There are many homes older than 50 years with susceptible timbers and the slow chewing of borer beetle larvae is now making more and more timbers fail. It might be too late for some parts of older houses but the borer damage can be stopped or at least slowed greatly by the use of protective borer products.

The cool damp conditions found in the south of New Zealand suit borer well and the homes of Southland, Otago and Canterbury suffer more than most from the ravages of borer. Borer control can be carried out effectively by the use of borer fluids that penetrate deep into the affected timbers and provide protection for many years. Even the timbers that are hard to reach such as roof timbers and floor timbers can be given protection by the use of borer fumigators during the flight season. These kill the adult beetles that have emerged from the flight holes and stop them mating and laying their eggs back on the timbers. There are also aerosol injectors that can be used to treat individual flight holes in damaged painted or varnished wood. This will kill larvae deep within the wood and prevent eggs being laid in the holes.

This is a good time to examine your home for sign of borer infestation. I suggest looking for fresh flight holes. These will have a clean appearance inside the hole. It may take examining the holes with a magnifying lens. Sand like dust known as frass may also fall out of the flight holes when the wood is given a tap. So check your home and protect it from damage now before you fall through the floor.

Surveyor: “This house is a structurally unsound. I wonder what is keeping it from falling down.
Owner: “I think the woodworm (borer larvae) are holding hands.”

Good Morning Followers……….or should that be follower?

I have such an ‘interesting’ life. I am off to the National Possum Control Agencies Technology Transfer Conference in Wellington this evening. It will be two days of hearing about and talking about the best ways to stop possums damaging New Zealand’s environment and transmitting tuberculosis to cattle, deer and other animals.

1080 is a popular subject for discussion among delegates. Most of those in the industry would welcome an alternative if it was as cost effective or the money was forthcoming to use the more expensive options that already exist.

Kiwicare manufactures NO Possums Cholecalciferol Gel Bait which is a very novel bait. It will remain effective over long periods (up to 26 months) so that time spent replacing deteriorated bait is saved and control is maintained over extended periods. The gel formulation and use of choleclciferol (vitamin D3) as the toxin makes the bait unattractive and of low toxicity to birds. Cholecalciferol also has low eco-toxicity as it does not build up in the food chain reducing risks of secondary poisoning of scavengers. The bait is available for use by anyone wanting to control possums, even if it is only to stop them eating the roses in your garden or you want to protect the block of native bush on your lifestyle block. It does not require a licence.

Enough of possums! I was supposed to be talking about borer. A rather different type of pest problem. Borer (also known as woodworm) are small brown beetles whose larvae eat their way through soft timbers including our weatherboards, floorboards, joists and furniture. You will know you have a problem with borer if you see small holes (flight holes) in your wood as if someone had thrown a dart into the wood. These holes are where the borer beetle has emerged after 2-4 years as a larva. The majority of these holes will be found in dark areas where the humidity is higher, e.g. under the floor, inside the walls and in a roof space if there is a roof of concrete or terracotta tiles.

The good news is that you can easily stop the borer damage. Treat the timber. If the timbers can be accessed they can be sprayed or painted with products that kill the larva and prevent new infestation for many years. On painted, varnished or polished surfaces the flight holes can be injected. Even when the affected wood cannot be accessed at all the use of borer bombs can control the adults and slow down their re-infestation of the timbers.

I have often heard it said that a house has never fallen down due to borer damage in NZ. This might be true, but it is only because most houses are only now old enough to have been that heavily damaged (it takes at least 50 years) and houses are condemned before they fall down.

This is the flight season (November-February) when adult beetles emerge from the timers and this is when borer bombs are most effective. The other treatments are equally effective at all times.

Save your property. Act now.

One woodworm asked her boyfriend. “How’s life?” she asked.
“Same as usual,” he replied, “boring.”