Other Common Names
Weevil wasps (applies to many but not all species of Cerceris but also applies to additional species)
Synonyms and other taxonomic changes
86 spp. in our area (of which ~30 reach Canada)(3)
, 29 in e. US(4)
, almost 900 worldwide(5)
Abdominal segments are constricted at the margins. Outer veinlet of submarginal cell 3 meeting marginal cell not beyond its outer third. Terga without median or submedian transverse depressions.
The faces of females are modified with unusual projections on the clypeus
and clypeal margin.
Females excavate cavities in soil as nests
Most species prey on adult beetles; some, on bees and wasps. At least one (C. halone), exclusively on acorn weevils (Curculio nasicus).
Females nest in aggregations in bare but firm soil. Sometimes females will use old nests of congeners or other wasps. In this case they prefer to dig their own tunnel from the old entrance instead of using the old one. While burrowing, some soil is not kicked but pushed in to form a plug. The burrow is a vertical tube that either has horizontal branches originating on it or has the main vertical tunnel itself becoming horizontal. Nests range from 2.5 cm to 1.3 meters in depth. Most nests probably average between 10 and 20 cm. After the main burrow is completed, females seem to begin hunting. Cells in some species are constructed from the entrance to the interior and others from the opposite direction. Cells usually number less than 10, up to 15-20 may be stored per cell. Up to 60 have been recorded. The female may leave the nest entrance open when away to hunt but will at least partially obscure or seal it after it returns with prey. In addition to weevils, they are known to provision with Scarabaeidae, Cerambycidae, Tenebrionidae, Buprestidae, and Chrysomelidae. Parasitic velvet ants (Mutillidae) have been reared from their nests. One species is known to have daughters assist their mothers in nest guarding.