Female: 10 mm. Male: 8 mm.
Eastern United States, eastern Canada, south eastern England, central Europe and Scandinavia
Great versatility of nests: some in pre-existing holes in various situations, reports of nests under stones, in masonry, in tree stumps (often in old beetle burrows), under bark and in crevices of tree trunks, in empty galls of cynipid wasps. Also completed nests may consist of ten or more cells arranged in a block.
One brood a year.
An introduced species, 1967 or earlier. A Palaearctic species according to Notes on Auplopus carbonarius
"Nests may have been brought into this country in nursery stock or wood products."