Wood Borer in the building structure


Wood Borer is a very common invader pest in New Zealand- many pre seventies homes have Borer to some extent in the structure somewhere. Often Borer is found in damper areas where there is some airflow. Damp conditions can make wood more susceptible, however most homes in New Zealand are at the desirable moisture content range to host Borer comfortably. The wood type utilized in the home plays a role in the infestation progress- some timbers are more acceptable to Borer having more available sugars in the wood. Bare wood and sawed timber allow easier penetration and will often be attacked initially over harder wood with a smooth surface as will Timber with higher moisture content.

There are several known Borer types in New Zealand with only three generally found in structures. The Two toothed long horn is the most infamous- it is a close relative to the Huhu grub, it is large in size and will seriously damage a site structure in one life cycle- their presence is obvious and infected wood should be cut out and burned- the surrounding unaffected timber should be professionally preserved. This species is relatively rare inside the home but the Common house Borer is not. Much smaller in size their damage is less aggressive but their life cycle is much shorter and they multiply faster- damage is often more intrusive than observed.  

Modern day timber treatment effectively prevent infestation, however this was not always the case, in the fifties it was becoming common the heat treat timber at the mill. This is said to be effective at killing Borer, however this does not protect even marginally against post milling introduction. This is where most Borer’ is suspected to originate in the home. 

Post milling treatment- many homes in New Zealand need to be treated at some stage for Borer infestation, in order to preserve structure strength and mitigate further damage. There are three main treatment methods utilized for structural Borer


  1.     Boron treatment.


This is a method often referred to as wood preserver. This treatment usually in wettable powder form and is mixed as concentrated solution with water and is either sprayed or most often painted on wood- The ingredient is usually Boric acid- it is considered safe for humans and is sold without a licence requirement, this is usually the choice of the do it yourself method. In large applications it is tedious work and will work out less cost effective than other common method. The down side to this treatment is, the product cannot be utilized with solvent carriers and so penetration into the wood is very limited – penetration is very important in a complete Borer control operation. Also Boric acid will only control Borer when the wood treated is ingested. Borer spend much of its time inside timber chewing around for years without feeding on the timber, rather making more space to be occupied by offspring. Boric acid will kill the Borer when it finally exits your home, it may prevent further eggs being laid as a result. This treatment is not suitable where there is moisture present as it will become inactive over time.

  1. 2.       Water applied insecticide


This is by far the most common method employed by Pest control companies in New Zealand. It is the most practical to apply and cost effective method. The very limited amount of solvents in the mix means a nil fire risk- in most situation specialized fire proof equipment is not required in the application. The insecticide is a controlled registered eco toxin and must be applied only by a professional. Most operators will utilize a selection of an Organic Pyrethroid group of chemicals. One common type is Permethrin- this synthetic Pyrethriod is considered a safe solution for long term control in the family residence. It is fortified to resist breakdown from moisture and sunlight. Unlike Boric acid these treatments will kill Borer on contact- they can also be adjusted to control the larvae and the Borer life-cycle. The limitations of these treatments are the inability to penetrate deeply into the wood – this is very important in complete Borer control. Test have shown even when ample water is used, penetration is very limited. This treatment however is more persistent then Boric acid and when professionally applied it is very feasible control will be gained over time- however it may not prevent Borer from further damage before the target makes an exit.    

  1. 3.       Solvent suspended insecticide


This method is not very common even with professional applicators. However it is hands down the best control available and is superlative to other options. Solvent suspension is the only method which can guarantee a complete control to timbers treated- insecticides utilized for Borer control actually have a considerably longer life  when mixed with solvents as opposed to water- hydrolysis will induce early inefficacy in both organic and synthetic insecticides this is not an issue with solvents. Testing has confirmed where solvents are utilized in timber control- within seven hours the majority of the timber is saturated with insecticide- in other words, the control treatment absorbs into the wood almost all the way! A twenty four hour period and the timber is over 90% completely saturated. The downside of this treatment is the cost of the materials are higher- the solvent type most utilized is flammable during application and drying- specialized equipment is required in the application as utilizing standard method is not safe.  More costly solvents which have been engineered to lower flammable ratings may be utilized and replace than standard solvent. 

The upside of this treatment method is the control is complete – in many cases it will kill the adult Borer and it’s full life-cycle 24 hours post treatment, period.

Contact us today to schedule a Borer inspection

Client Feedback

"Paramount Pest Control Auckland did the Borer Treatment at my house. They arrived on time, the work was done neatly, and the price was low compare to the other companies. I would strongly recommend them to anyone in need of borer services. Thank you Reuben for this wonderful service."

Gary – Remuera, Auckland