Renter: Existing cavities.This species nests in burrows of appropriate diameter in various substrates, including dead trees and fence posts; Currie (1954) found a large and flourishing aggregation in some old fence posts on Box Hill, Surrey (there were more than a hundred occupied holes). Specimens have also been observed utilizing borings in decaying, wooden window frames (Yarrow, 1954a). D.B. Baker (pers. comm.) has seen females nesting in dead, broken Rubus stems on Oxshott Heath, Surrey. A specimen has also been observed inspecting fissures in the masonry of a house wall in Midhurst, West Sussex (pers. obs.).
In France, Laboulbène (1873) reports a nest containing ten cells of this bee in a hollow vine stem. Continental nests have been described by Grandi (1961) and Correia (1976), the latter also illustrating cells and all developmental stages from egg to adult. Females construct cell partitions and the closing plug from resin, collected from conifers (Correia, 1977) or from both conifers and broad-leaved trees (Westrich, 1989). esin collection has not been observed, but it is presumably transported to the nest in the bee’smandibles: in Surrey, Nevinson (1907) noted a specimen with a lump of this material adhering to its mandibles. The partitions usually consist of pure resin, without obvious additives (Käpylä, 1978), but occasionally they may be constructed from a mixture of earth and resin (Käpylä, 1978; Grandi, 1961), a mixture of plant fragments and resin (Correia, 1976), or a combination of decayed wood and resin (Käpylä1978). In the latter example Käpylä considers that the addition of wood particles to the outer resinous surface of the closing plug may assist in camouflaging the nest entrance.
Cells are arranged linearly and the side-walls of each are not lined with any foreign material. Opened, completed nests, along with females sealing the nest entrances, are illustrated by Westrich (1989), Müller (1990) and Müller, Krebs & Amiet (1997).
The full grown larva spins a cocoon within which it overwinters, pupation taking place the following spring