One particular group of old wood blocks functions well as nest location for digger wasps. I observed two separate wasps entering the block on two different locations and it turned out they were nest building Crossocerus annulipes .
The entrance to nest 1 was located in a hole at the underside of the block. To enter it the wasp would land in front of it and walk in.
Apparently there is more than enough prey present in the garden as the wasp flew off and on with an interval of about 2 minutes, bringing home cicadellidae. She stayed in the nest for 1-3 minutes before starting the next hunt.The prey is transported belly to belly and held in position using the middle and hind legs.
The entrance to nest 2 was located in a crack about a centimetre above ground. The wasp would land on the wood just below it and crawl in.
References1 Nederlands Soortenregister