Gasteruptiidae is represented by perhaps 1500-2000 species worldwide (Jennings and Austin 2002), of which about 500 are described. It is divided into three subfamilies:

• Kotujellitinae - fossil subfamily containing two monotypic genera fromthe Late Cretaceous of northern Siberia and the mid-Early Cretaceousof Mongolia (Basibuyuk et al. 2002)
• Gasteruptiinae - extant subfamily with one genus (Jennings and Austin 2000)
• Hyptiogastrinae - extant subfamily with two genera (Jennings and Austin 2000)

The larvae of Gasteruptiidae are reported to be predators or predator-inquilines of various solitary bees and wasps (e.g. Höppner 1904; Malyshev 1966; Carlson 1979, Jennings and Austin 2004). Various authors have used the term secondary cleptoparasitoid (synonymous with predator-inquiline) (see Valentine and Walker 1991) or ectoparasitoid (synonymous with predator) (see Prinsloo 1985) when referring to gasteruptiids.