Timber Borers – What are they and Should I be Worried about my House?

Timber Borers commonly cause damage to old floorboards and framing timbers, but are they capable of major structural damage, in the Sydney area?

Wood borers (timber borers) are a type of timber pest we report on and include insects that live on / in timbers, often before these timbers go into service. Most are related to beetles, moths and wasps who lay larva in timbers that hatch, leaving holes in the surface of the wood. This borer damage is often resembling ‘shot holes’, pin holes or ‘wriggly patterns’ in the surface of the wood. Some species attack live trees, some dead trees and some live on dead wood. Certain borers can have an adverse affect on the structural performance of timber in use in the construction of buildings, although in our experience the issues are usually cosmetic damage.

The main timber borers we encounter during our inspections in Sydney include:

  • Anobium Borer damage – commonly found on old timber floor boards in terraces, workers cottages, federation homes and other older style buildings. This damage is usually inactive and does not require treatment. However the affected floorboards are weakened and can be a safety hazard, breaking under foot.
  • Lytus Borers attack the sapwood of certain Australian hardwoods. As these hardwood framing timbers are graded before they go into service, they should not contain more than 25% heartwood, therefore not posing a structural concern in larger cross sectional timbers such as framing. However small timbers like roof tile battens, can be structurally compromised in more extreme cases, requiring replacement.
wood borer larva grug illustration

Timber Pest Inspectors have a thorough knowledge of the various types of timber borers likely to be found in Sydney properties, they are able to identify them and make recommendations on if this requires further action.

In some cases evidence of timber borers does not become apparent until the borer has emerged via an exit hole in the surface of the timber, or in the surface of the lining such as plasterboard. This can be long after the timber is installed.

Life Cycle

Timber borers generally undergo complete metamorphosis. From Egg – Lava – Pupa – Adult. It is the Lava stage of the borers life that the damage occurs to timber.

The eggs are laid into the timber, eggs hatch, larval stage feeds on the timber and insect pupates and emerges through the timber surface in the adult form.


Identification of the type of borer can be difficult, as the adult insect is not found at the site of damage. Therefore the skill to identification involves identifying the type of timber, the nature of the damage and other evidence found at the site such as timber dust or frass. Some borer holes do not have structural consequence, others do.

For this reason a Timber Pest Inspection by a trained professional is strongly recommended.