A series intended to be a tool for identifying the European micro-moths. Each volume will treat a systematic unit comprising about 100-300 species. This will usually mean a family or subfamily, but it can also be a single large genus, or a group of smaller families. Small and systematically unrelated groups may also be collected in one volume. The geographical area covered will be Europe west of the former U.S.S.R., and include the Baltic countries. Authors may also include the adjacent parts of the western Palaearctic Region, i. e. Macaronesia, North Africa, Cyprus, Turkey, the European part of the former U.S.S.R., as well as Transcaucasia. Each volume will illustrate the adults of all species in full colour, either by colour photographs or water-colours. Sexual dimorphism and extensive polymorphism will also be illustrated. All species, except the largest, will be shown enlarged.