Renter: Existing cavities. The lateral walls and partitions of the cells, and the closing plug are constructed from damp soil (clay or sand). Nests are established in existing cavities, including abandoned nesting burrows of other insects in the soil (Ferton, 1896), in walls (F.K. Stöckhert, 1933; Niemelä, 1936), in a dead Phragmites stem (Ferton, 1896; F.K. Stöckhert, 1933), in a cane (van der Zanden, pers. comm.), and in a small stem of Castanea sativa (Grandi, 1961). A free-standing nest attached to the underside of the roof of a beehive is described and figured by Grozdani & Mu alica (1968). Ferton (1897) figures a nest in a Phragmites stem. In most nests the cells appear to be arranged in a linear series. The outer surface of each cell is very rough, being composed of numerous agglutinated pellets of mud, each pellet being individually collected and added to the structure. The internal cell surface is smooth and polished, and often uniformly coated with a thin film of resin, except for the inner wall of the partition; the outer face of the closing plug may also be varnished with resin, but not its inner surface (Ferton, 1896). In some nests only patches of resin may be added (Grozdani & Mu alica, 1968). An apparently free -standing nest in the NHML does not show any indication of resin having been used in its construction (pers. obs.). A nest is figured in Banaszak & Romasenko (1998).