The Elachistidae (Lepidoptera, Gelechioidea) of Northern Europe are monographed. The seventy-seven species in six genera constitute the species hitherto recorded from Finland, Sweden, Norway, Denmark and Great Britain and nine species currently known from adjacent regions. All taxa are keyed and described. Both sexes are illustrated in full colour, the plates being accompanied by diagnostic characters. Wing venation, male and female genitalia of all species, and many leaf-mines are illustrated.
Twelve of the treated species, including kebneella sp.n., are arranged in a new genus Biselachista gen.n. Three additional Western Palaearctic and ﬁve Nearctic species are placed in new combination with Biselachista gen.n. Females of Elachista parasella Tr.-O., E. Iittoricola Le March. and Biselachista abiskoella (Bengts.) are described for the ﬁrst time. One neotype and seventeen lectotypes are here designated.