Seven species (A. calcaratus, A. concolor, A. luxus, A. niger, A. notabilis, A. feralis, A. hirsutus.
A. hirsutus is in the subgenus Plectraporus, the rest are in the subgenus Aporus.
Typically 8-15 mm, although males may be slightly smaller and females slightly larger than the figures given here; females>males.
This genus belongs to the subfamily Pompilinae, tribe Aporini and is identified by the following characters:
Spines at apex of hind tibia of unequal length and spacing.
Hind tibia always smooth in nearctic species.
Dorsal side of hind femur with at least a few spine pits.
Pocket in the basioposterior corner of the third discal cell.
Labrum at least partially concealed.
Females of this genus lack a tarsal comb.
Only two submarginal cells in the anterior wing.
Pronotal collar not depressed and on the same plane as the thoracic dorsum.
Pronotum very long, usually much longer than mesonotum, its posterior edge straight.
All species and both sexes are black, some have a fine pubescence that reflects bluish or greenish.
Transcontinental as a genus, but only two have been recorded east of the Mississippi River and one (A. calcaratus) is restricted to southern Florida. A. niger is relatively safely identified in most of the east.
Varied, from deserts to deciduous forests.
Varied, depending on species and range. Aporus niger is in flight in the east from mid-June through September.
Adults occasionally visit flowers. Spider prey is unknown for all but one species, but in those that are known the prey are Cyraucheniid spiders. However, A. niger is found in places where Cyrtaucheniids are absent, so it is possible that they feed facultatively on other spider species. Their prothoracic structure is modified for feeding on burrowing spiders and they likely prey on cyraucheniids where present.
Apparently does not use its own burrow, but enters the burrow of a Cyrtaucheniid spider, paralyzes it, and then lays an egg. In southern states there can two generations per year, in the north there is apparently only one.
Bradley, J.C. 1944. A preliminary revision of the pompilinae (exclusive of the pompilini) of the Americas. Trans. Amer. Entomol. Soc., 70:23-157 (most descriptions and keys still are valid/work).
Krombein, K.V. 1979. Pompilidae, pp. 1543-1544. 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. (species, distribution, references)
Evans, H.E. 1966. A revision of the Mexican and Central American spider wasps of the subfamily pompilinae. Mem. Amer. Entomol. Soc., 20: 1-439. (more current descriptions can be found for most western species, keys)