In Britain, P. eremita nests in pine bark, in burrows in the bark and dead sapwood of pine and deciduous trees, and in abandoned beetle borings in posts, the nest entrances frequently being surrounded by a ring of small drops of resin (a feature which is possibly unique to this species (G.R. Else, pers. comm.)). The nests are also sealed with resin, which hardens to a characteristic white or off-white plug (Else 1997). In Denmark, the species has been found nesting in the hollow stems of common reed used in thatching roofs, sometimes in very large numbers. There are usually 4 or 5 cells per reed stem, terminating in a vestibular cell. The last constructed cells usually contain males, which are the first to emerge. Burrows in bark or old timbers frequently have one or two cells only (M. Edwards, pers. comm.). A previously occupied stem or beetle boring may be re-used (Lomholdt 1975-76).