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These wasps are antlike in appearance (Manley and Pitts 2002). Compound eyes somewhat hemispherical. Felt line only present on tergite II. Dorsal setae uniformly light orange to red (Manley and Pitts 2007). Females: Wingless. Setae not plumose (Manley and Pitts 2002). Head much narrower than mesosoma, which lacks a scutellar scale (Manley and Pitts 2007). Antennal scrobe carinate dorsally. Sternum II pitted. Males: Winged. Posterolateral angle of the last sternite dentate. Mandibles lack notches ventrally (Manley and Pitts 2002). Wing venation normal with a sclerotized pterostigma. Axilla prominent and notauli absent. Two spurs present on mesotibia.

Solitary ectoparasites of ground-dwelling wasps and bees (Mickel 1928). Adult females enter host nests and deposit eggs into diapausing larvae or pupae (Arnesonand Pitts 2003). The parasitic larvae then consume the entire host before entering the prepupal stage (Mickel 1928). The size of adults is believed to depend directly on the size of the host larva. Thus, host availability may be the cause of geographic, seasonal, and annual size differences (Deyrup and Manley 1986). Also, females may determine whether to release or withhold sperm upon oviposition depending on host size. As they search for hosts, adult females build new retreats daily (VanderSal 2008). Adults are inactive midday when temperatures are highest (Mickel 1928); however, females have a higher tolerance to high temperatures than males. This is likely due to their reduced mobility. Adult females are reputed to have a very painful sting.

Currently known larval hosts: Anthophora occidentalis (Cresson), Diadasia enavata (Cresson), Diadasia bituberculata (Cresson), Diadasia nitidifrons (Cockerell), and Megachile perihirta Cockerell (Manley 2007). It is speculated that adult females eat nectar and larvae from host nests (Brothers 1989).

Saskatchewan and Alberta. North Dakota south to Texas, west to California and Oregon. Recorded from the following states in Mexico: Aguascalientes, Chihuahua, Durango, Nuevo Leon, Veracruz, Zacatecas and south to Oaxaca (Manley and Pitts 2007).