This genus comprises a heterogeneous group of small colourful species ranging from 2 to 7 mm in length. Characteristic morphological features include the single perpendicular tooth of the tarsal claw and the transverse pronotal carina (Kimsey and Bohart 1991). The posterior margin of T3 is evenly rounded, without any angular projections. The biology of most species is poorly known, but according to published records, the larvae develop as nest parasites of ground-nesting crabronid wasps and solitary bees. Hedychridium is the second largest genus of Chrysididae and includes more than 300 recognised species worldwide. The highest diversity is found in arid parts of the Holarctic Region and southern Africa. A total of 86 species are known from Europe (Rosa and Soon 2012). Of these, seven occur in the Nordic and Baltic countries (Paukkunen et al. 2014). The genus is here divided into three species-groups according to Linsenmaier (1968, 1997).