Renter: Existing cavities. This bee nests in existing burrows in dead wood and masonry. For example, E.S. Bradford (pers.comm.) reared two individuals of this species from nests in wooden window frames at Chestfield, Kent. It will also utilise trap-nests consisting of bundles of drinking straws (Raw, 1974).
Nesting material: The cell walls have been described by R.C.L. Perkins (1891b) as being prepared from chewed Rosa leaves, which were usually yellow and decayed. An opened nest showing cell contents is illustrated by Müller, Krebs & Amiet (1997). (Banaszak and Romasenko, 2001; Benoist, 1931; Friese, 1923; Grünwaldt, 1939; Malyshev, 1937; Müller et al., 1997; Romasenko, 1980; Westrich, 1989)
Osmia leaiana apparently has an obligate two-year life-cycle in Germany (P. Westrich, pers. comm.). This may occur too in the British Isles as Raw (1974) discovered that in specimens that he studied, 12 individuals spent the first winter as prepupae in their cocoons, and the second as adults which emerged in the second spring.