A composition or concentrate for preserving wood, which comprises 0.001-5% by weight of cyano-(4-fluoro-3-phenoxyphenyl)-methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate and/or (pentafluorophenyl)-methyl 1R, 3R-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate or enantiomeric compounds thereof and more than 75% by weight, preferably more than 90% by weight, of a mixture comprising at least one binder at least one diluent, and optionally at least one emulsifier and/or wetting agent or mixture thereof. The binder in the wood preservative or concentrate (calculated as solids) amounts to at least 1% by weight, preferably at least 4% by weight of the composition. An alkyd resin and/or a vegetable drying oil is preferably used in the composition as the organic binder for preventing or reducing damage to beneficial insects.