Excavator: Ground. Nests are built in an excavated short burrow in hard soil. The burrow entrances are hidden under small shrublets. For each cell, a more or less vertical burrow (1.5cm deep) is excavated in rather hard soil. Up to 10 cells are built immediately beside each other separated by few millimeters only. The cells of a single nest – when removed from the soil – partly adhere to each other by small earthen bridges.
Nesting material: The cells (ca. 1.5cm long) are entirely built of petals (e.g. of Helianthemum) and mud. The cell walls are usually three-layered: the outer layer consists of small to large petal pieces glued together with mud, rarely with small pebbles as well; the central layer consists of a thin layer of mud, which is sometimes only weakly developed; the inner layer is composed of 6-10 layers of large petal pieces without any addition of mud. After egg deposition, the cell is closed by folding over the inner layer of petals. Afterwards, the cell cap is built which is composed of two layers: the inner layer is rather thick and consists of small petal pieces glued together with mud and small pebbles; the outer layer consists of a thin wall of petal pieces neatly glued together. Occasionally, the cell cap is rather three-layered with an inner layer of small petal pieces, a central layer of mud and small pebbles and an outer layer composed of a thin wall of petal pieces. In the end, the cell cap is hidden under a thin and loose layer of sand and small pebbles. (A. Müller, personal observation; Rozen et al., 2010).