Cleptes females search for tenthredinid and diprionid sawfly cocoons either on the host’s foodplant or on the ground beneath and lay one egg per cocoon (Morgan 1984). The emerging larva develops as an ectoparasitoid of the sawfly prepupa within the cocoon (Darling and Smith 1985, Kimsey and Bohart 1991). The genus consists of around 100 known species, the majority of which occur in the Holarctic Region (Kimsey and Bohart 1991, Wei et al. 2013, Arens 2014). A total of 27 species are known from Europe (Rosa and Soon 2012, Arens 2014) and three from the Nordic and Baltic countries (Paukkunen et al. 2014). We have divided the genus into species-groups according to Móczár (1997, 2001).