Mason. The females construct the nests on the surface of stone walls. The cells are made of a cement which is a mixture of sand, particles of earth, and saliva. The nest consists of 6-20 cells, covered with a common layer of mortar. The external surface of the cells is rough, but internally, they are highly polished. (Banaszak & Romasenko, 1989).
Le Goff (2007) reports that the cells are often hidden in holes in walls or under stones, or placed in existing holes in steep, hard soil slopes, under overhanging rocks (Müller et al. 1997), or as described by Fabre (1879, 1882) under the roof tiles of old barns; sometimes the nests are exposed on stones as in M. parietina.