The Asiatic, European and North American species of the genus Deroslenus Westwood are revised. Fivc species are recognized, two Asiatic, two European and one North American. The two Asiatic species are described as new: D. japonicus (female) and D. sulciscuta (male). Deroslenus alhipes Yoshimoto is regarded as a synonym of D. freemani Yoshimoto. The subgeneric division proposed by Yoshimoto (1973) is abandoned and two species-groups are created. One group (gemmeus) comprises the European and North American species, and the other group (sulcisuta) includes the Asiatic species. Lectotypes are designated for D. confarmis Thomson. D. laevifrons Thomson and D. punctiscuta Thomson. The European and North American specics are found to be solitary endoparasites in larvae of Stigmella spp. (Lep.: Nepticulidae). Hosts are not known for the Asiatic species.