Renter: Snail Shells: empty snail shells of small to medium size with a diameter of 15–30 mm, e.g. Otala lactea (Helicidae); nests were also found in elongate conical shells of Rumina sp. (Subulinidae) with a length of 24–32 mm and a diameter of 9–12 mm (Ferton 1920, A. Muller unpublished data) with 1-4 brood cells per shell. The nest architecture is the same as in Osmia (Hoplosmia) spinulosa (n=25 nests from Jordan)(Müller, 2018).
Nesting material: Cell partitions and nest plug are made of chewed leaves. The shell surface is not plastered with patches of leaf pulp. (Ferton, 1920; Mavromoustakis, 1948b; A. Müller, C. Praz and C. Sedivy, personal observation)
The brood cells are separated from each other by single-layered partitions consisting of leaf mastic. An additional wall of mastic seals the shell at, or few mm behind, its opening. The empty vestibular area between the outermost cell and the nest plug varies in length from one quarter to five sixths of one shell whorl. The nests are not sealed at their rear end with a basal wall, and the outermost cell partition is distinctly more robust than all the other cell partitions. The nest plug, probably acts as a barrier against parasites and predators.The shells are never turned after they have been sealed (Müller, 2018).