Mason. The bee constructs pot like nests made from a fine sand/saliva mixture. The nests are constructed on a suitable stone. Once construction of a cluster is complete, the female constructs a surrounding layer which completely conceals the individual nest cells. The nests are very hard and can persist for several years. Kronenberg and Hefetz (1984) have demonstrated that females of Megachile sicula add labial gland secretions to the mud; these secretions rapidly harden and render the nest hydrophilic (Praz, 2017). Megachile sicula builds nests both on twigs and on rock surfaces (Kronenberg and Hefetz 1984, Vereecken et al. 2010).
Fine sand is often collected on road and tracksides, especially on the outside of bends, where the finer particles can be found (S. Roberts, pers. obs.)