Typically not much larger than 10 mm
Identified as Pepsine by the groove in the second sternite, spines on the end of the hind tibiae being equally sized and spaced, labrum partially hidden, and no pocket on the basioposterior corner of the third discal cell.
Identified as Agenielline by the first tergite being concave near the base (this and very long, slender legs give a very slender overall appearance) and no serrations on the hind tibia.
Auplopus lacks a crease on the side of the first tergite that Phanagenia has. They have a bare pygidial area and two groups of very stout bristles on the underside of the head, both are adaptations for being mud daubers. One of the best characters, especially in well lit photographs, are the very long, erect hairs on the propodeum.
Most are found in woods but females are often found around and even in old houses. They apparently use cracks in the foundations as areas to build mud nests. They sometimes find their way inside the houses.
Males seem to emerge first and can be found fairly early (May). They can be found as late as October, or even later in southern states.
Adults are occasionally found on flowers. Females provision a mud cell with a single spider. They usually prey on spiders of the families Anyphaenidae, Clubionidae, Gnaphosidae, Thomisidae, Pisauridae, or Salticidae.
In most species there are several generations per year.
This genus is in dire need of revision on a worldwide scale.
The palearctic Auplopus carbonarius has also been documented in North America (see below).
Assigning the metallic green species that have all black legs is often difficult even with a specimen in hand; three species in particular: A. caerulescens, A. architectus, and A. nigrellus. All three are found in Kansas and they are all EXTREMELY similar. Townes (1957) even comments in his keys that the three species are often inseparable in the female (the males are rather easily separated). (Comment by Nick Fensler)
; very similar in shape and habits.
Townes H.K. (1957) Nearctic wasps of the subfamilies Pepsinae and Ceropalinae. U.S. Nat. Mus. Bull. 209: 1-286 (descriptions, distribution, and keys to species)
Krombein K.V. (1979) Pompilidae, pp. 1523-1571. In Krombein, K.V., P.D. Hurd, Jr., D.R. Smith, and B.D. Burks, eds. Catalog of Hymenoptera in America North of Mexico. Vol. 2 Apocrita (Aculeata). Smithsonian Inst. Press, Washington, D.C. (list of species, prey records, references, notes on distribution)
O'Brien M.F., Kurczewski F.E. (1992) Auplopus carbonarius, a Palearctic spider wasp, extends it range to Michigan (Hymenoptera: Pompilidae). Great Lakes Entomol. 24: 185-186.