A timber’s propensity to infestation by lyctine insects, principally the powderpost beetle Lyctus brunneus is classified as:
SL: Susceptibility to lyctines confirmed; (SL) considered susceptible (unconfirmed); NS Not susceptible to lyctine attack.
The sapwood of all softwoods (Pinus, Callitris, Picea, Larix, Araucaria, Agathis, Pseudotsuga, Thuja and Abies species) and the sapwood of some hardwood species are immune to lyctine attack (i.e. infestation and damage by the powderpost beetle).
The sapwood of all other (lyctine-susceptible) hardwoods is rendered non-susceptible to attack by lyctine borers when immunised by preservative treatment. Protecting sapwood in lyctine-suceptible timbers is based on a minimum preservative treatment to hazard level 1 (H1 or H level1). H1: In a well-ventilated place where the timber is kept off the ground and completely protected from weather and wetting—preservative treatment is designed to reduce the likelihood of attack by insects other than termites.
Another option for processors or suppliers is to remove lyctine-susceptible sapwood during processing.
The use of non-immunised lyctine-susceptible timber with a greater cross-sectional area than permitted under want and wane allowances in the relevant Australian Standard is not recommended in permanent buildings in Queensland.
All species recognised as non-susceptible to lyctine attack are listed with the symbol NS. All other species are considered lyctine-susceptible. Where laboratory tests confirmed susceptibility, the symbol SL is used. All other, unconfirmed but potentially susceptible species are identified with the bracketed symbol (SL).