Borer Treatments

Borers of seasoned timber are generally beetles. The adult stage lays eggs, which hatch into larvae. The larval stage causes the damage by burrowing through and consuming the timber. The larvae pupate, then cut out through the timber when adult, in order to start the life cycle again. It is normally the cutting out process which is the first sign of borer infestation.

The borer which commonly attacks hardwoods is known as “The Powderpost Beetle” (Lyctus brunneus). These borers only attack the sapwood areas of hardwoods and normally within the first 12 months of service. They only lay eggs in this region because the female’s ovipositor fits into the xylem vessels of hardwoods, which are a large vessel found only in the pore structure of hardwoods. The “Timber Marketing Act” limits the amount of sapwood that can be present in hardwood timbers, and ranges from 25% in structural members to 0% in finishing elements. A time span of 24 months exists for the consumer to take action against the supplier, builder, and retailer. The Act is administered in Queensland by the Department of Primary Industries. Most of the time, no action is necessary when these borers or their damage is located, however it is always wise to have it inspected by a specialist.

Borers which attack softwoods in Queensland are normally either “The Furniture Beetle (Anobium punctatum) or “The Queensland Pine Beetle” (Calymmaderus incisus). These borers normally only attack certain softwood species which have been in service for 20 years or more, and can re-infest. Their damage is often found in floorboards and v-j wall linings, and has the appearance of squiggly lines on the top surfaces, and emergence holes of 1 – 2 mm diameter on the underside. The infestation can be chemically treated annually for a 3 year period (which breaks the life cycle); however the long-term solution is to replace the timber with a non-susceptible variety.

As always, Mother Nature throws us curve balls, and there are many other borer species that can cause problems. The “European House Borer” (Hylotrupes bajulus) can cause devastating damage, and an infestation of this beetle initiates the involvement of Government Authorities including the Quarantine Department. In addition, green timber borers can be introduced to houses when buying timber articles. For example “Longicorn Beetles” can pupate in a state of suspended animation for some time, and so if someone buys a timber bowl and the adult beetle emerges, it can cut out through the article and the furniture it is placed upon, but will not re-infest any seasoned timber.

The identification of borer damage and the species that caused it is a specialist job, which needs to be conducted by an adequately licensed inspector. It is sometimes very difficult to establish the difference between an active infestation and old damage.