The following material taken with permission from: Mitchell, T.B. 1962. Bees of the Eastern United States, Volume II. North Carolina Agricultural Experiment Station. Tech. Bul. No.152, 557 p.
These are very coarsely sculptured, parasitic bees, usually black, but ferruginous in part in some of the species. The abdomen in the females tapers posteriorly, often acutely pointed, while in the males it is multispinose at the apex. They are parasitic on species of Megachile and have some characters in common with that genus. Thus the notaulices are linear, there are no arolia between the claws, and the basal abdominal tergum is shallowly concave anteriorly. In the males sterna 1-4 are exposed, 5 is largely hidden, while 6 and 8 are retracted, with 7 not represented by a sclerotized plate. Tergum 6 forms the apex of the male abdomen, usually with three pairs of spines or carinae, one dorsal, another ventral, and a shorter pair lateral in position. As in Megachile the true apical margin of the tergum is on the ventral surface. Tergum 7 is much reduced but is usually to some degree visible, while 8 is entirely membraneous. The male genital armature is relatively simple and unmodified. In both sexes the metanotum and posterior face of the propodeum are perpendicular, the scutellum quite broad and the axillae usually angulate, often conspicuously produced or spinose. The front coxae of both sexes have a pair of robust spines in most species; the pleura are divided into anterior and lateral faces by a vertical carina; the tubercles are carinate; the maxillary palpi are 3-segmented; the mandibles are 3-dentate; and in the front wings both recurrent veins are received by the 2nd submarginal cell. In the conspicuously hairy eyes they differ from all of the related genera of bees.