Renter: Existing cavities. Females of this species select various kinds of existing cavities in which to nest. Sites include burrows in dead trees and decaying woodwork, in woody stems, in the soil, cavities in masonry and under stones.
Unusual situations include the metal guide groove of a casement window (Michelbacher & Hurd, 1954), a space between the folds of a carpet roll which had been inserted against a rafter of a shed (Medler, 1959), and under roof boards.
A nest in a bamboo stem is illustrated by O’Toole & Raw (1991). Medler also briefly describes and figures nests, and concluded that a female is capable of constructing at least thirty cells during her life. As is usual in non-cleptoparasitic Megachilinae, male cells are generally located nearest the nest entrance, although some nests may only contain one sex. Medler believes that all-female or all-male nests are partial nests. Danish nests are described by Holm & Skou (1972), who also observed that females were consistently reared in the innermost cells, and males in the outer ones. Raw (1988) demonstrated that the species is protandrous.
In Britain, cell walls and partitions are fashioned from various leaf sections, including those of Rosa, Circaea lutetiana and Hypericum androsaemum (G.M. Spooner, pers. comm.), and in Denmark Betula, Syringa, Castanea, Fraxinus and Lonicera sections are additionally recorded (Nielsen, 1902). Holm & Skou (1972) found that the closing plug of a nest may contain 30-40 separate leaf pieces. Groups of cells and prepupae, plus an entire nest in a dead, sectioned
Phragmites stem, have been described and figured by Grandi (1961). Markowsky (1933) describes a nest in which only the cell partitions were constructed from
leaf cuttings, the side walls not being lined in any way. Romasenko (1990) figures a nest of this species. Newport (1845) observed a female of this bee bringing finely shredded white cotton cloth to her nest burrow in a brick wall. Later, on separating two bricks to disclose the nest, he found that the base of the burrow was uneven, being full of cavities. These the bee had filled in with the cotton, so presenting an even surface around which she placed cut Rosa leaf sections which formed the cell walls. Raw (1988) describes the nesting biology of this species in southern England.
The winter is passed as a diapausing prepupa within a tough cocoon.