A new digger wasp species on the bee hotel, Crossocerus annulipes . Three females had built their nests in a deep crack in the side of nestblock 7 in section III. I have not been able to see whether they used the same main entrance or build separate entrances, both is possible. The species showed some interest in the artificial drill holes but eventually chose to built their own nests.
In front of the entrance a pile of sawdust vcollected, which was carried back in a later stage inside the nest by the wasp using her mandibles, to close up the corridor to the filled brood-cells.
I’ve caught one of the wasps for identification, see here.
In 2021 the wasps returned
References1 Nederlands Soortenregister