Opened nests of Osmia pilicornis in dead branches (see Table 2): 12 Nests 1 and 2 with three and two brood cells, respectively, each containing a cocoon spun by the O. pilicornis larva 13 Nest 3 with one brood cell containing a cocoon spun by the O. pilicornis larva; at the bottom a pupa of Molorchus minor (Cerambycidae) 14 Nests 4 and 5 with two and one brood cell, respectively, each containing a larval provision; an empty vestibule is present between the outermost cell partition and the nest plug in nest 4, while the cell partition is part of the nest plug in nest 5.