Renter: Existing cavities. The species has been found nesting in cut bamboo trap-nests (diameter 6mm) at altitudes of 1430-1800m in Switzerland. A mixture of mud and small stones was used as a building material for partitioning the cells.(Frey-Gessner, 1880; Friese, 1923; Westrich, 2002; A. Müller, personal observation).
Westrich also states that the nests vhe investigated had 3 or brood cells inside each stem.
The nest closures were made of a pale muddy mortar, and were approximately 4.5mm thick.