This part of the EN 20 series specifies a method for the determination of the protective effectiveness or the toxic values of a wood preservative against infection by Lyctus brunneus (Stephens) when the product is applied as a surface treatment to wood. This method is applicable to: - water-insoluble chemicals which are being studied as active insecticides; or - organic formulsation, 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 materials, for example salts. NOTE – This method can be used in conjuction with ageing procedures, which do not remove the added nutrient.