Excavator; Ground. Details from Müller (2018): The nest is constructed in the soil, each burrow ending in 1 or 2 brood cells decorated with cut petal fragments of Malva sylvestris (Malvaceae).
Excavated burrows (2-6cm deep) in horizontal or vertical hard soil with 1-3 linearly arranged cells. The females sometimes also use preexisting insect burrows in the ground. Romero (2019, in litt.) reports a small nesting aggregation in Catalunya
Nesting material: The cells are entirely built of two to three layers of petals mainly of Malva, Althaea and Lavathera, occasionally also of Ononis. The partitions between adjacent cells and between the last cell and the nest plug are three-layered: a layer of mud and small pebbles between two walls made of chewed petals; these partitions sometimes also consist of masticated petals intermixed with mud and small pebbles. The nest burrow is closed immediately below the soil surface by a wall built in the same way as the cell partitions, sometimes however larger pieces of petals are used than for the cell partitions; this wall is eventually hidden below earth crumbs. The space between the last cell partition and the nest plug is loosely filled with crumpled petals. (Benoist; 1931; Ferton, 1892, 1897; Grandi, 1961; G. Le Goff, personal observation; Müller & Richter, 2018)