This document specifies a method for the determination of the eradicant action of a surface application of a fast and a slow acting wood preservative product or a deferred acting wood preservative product on timber infested with larvae of Hylotrupes bajulus (Linnaeus). This method is applicable to: organic formulations, as supplied or as prepared in the laboratory by dilution of concentrates; or organic water-dispersible formulations, as supplied or as prepared in the laboratory by dilution of concentrates; or water-soluble products, for example, salts. NOTE An ageing procedure cannot be combined with this method.