The Canadian Entomologist
Prof. Westwood and others confused these wasps with the Vespidae and the Eumenidae, although Latreille had years previously established his family Masarides. Henry de Saussure, in his "Etudes," treats them as a tribe. They, however, represent a distinct family close to the Eurnenidae, but easily separated from them and the Vespidae by the wings not being folded longitudinally, by peculiarities of the antennae, which are usually strongly clavate at tip; by the wholly different abdomen, the venter being flatter; and by the much larger scutellum.
Ashmead, William H., "Classification of the Fossorial, Predateous and Parasitic Wasps, or the Superfamily Vespoidea No.8" (1902). An. Paper 88.