The Canadian Entomologist
The globose or rounded head, which is never flat, oblong, and the difference in the antennae, the antennae in males being 10-jointed, in the females 13-jointed, readily separate the subfamily from the Bethylinre. The group comes quite close to the Dryininae, but in the latter the head is transverse or subquadrate, never rounded, while the antennae are 10-jointed in both sexes.
Ashmead, William H., "Classification of the Fossorial, Predateous and Parasitic Wasps, or the Superfamily Vespoidea No.10" (1902). An. Paper 82.