Book excerpt: Many species of Drosophila are very important laboratory animals in almost all fields of biological research, because of the ease of culturing on artificial media as well as of their rapid rate of development. Also the study of natural populations, including their living conditions, has become more and more important. "The Drosophilidae (Diptera) of Fennoscandia" gives a detailed account of the taxonomy, identification, distribution, and biology of 17 genera and 128 species of West European Drosophilidae. Full descriptions and standardized illustrations of the terminalia are provided for 80 North European species. The aims of this books is to faciliate field work by providing identification keys and by giving hints for further studies on biology, distribution and other aspects of drosophilids.