A cladistic analysis of the subgenera of the paper wasp genus Polybia Lepeletier (Hymenoptera: Vespidae; Polistinae), and the other genera that construct phragmocyttarus nests, is presented. The results clearly indicate paraphyly of Polybia in terms of the genus Synoecoides Ducke. To remove the paraphyly, Synoecoides is reduced in rank, to a subgenus of Polybia, new synonymy.