The Canadian Entomologist
This family, although quite distinct, is closely allied to the two which follow-the Myrmosidae and the Mutillidae-and it will probably be difficult for the student to separate at once the wingless females from some in the families mentioned. Some authorities, having been unable to find good characters to separate these wasps, have classified all together as a single large family under the name .Mutillidae; but I think incorrectly so.
Ashmead, William H., "Classification of the Fossorial, Predateous and Parasitic Wasps, or the Superfamily Vespoidea No.13" (1903). An. Paper 81.