A remarkable observation on 12 July. A female Ectemnius appeared on a nest block with a prey that looked like a fly. She crawled along the wall behind the nest block. Unfortunately I had no time to grab my camera. At the end of the season I will try to remove the nest block and see what she has build.
Later on the day another female appeared, possibly the same specimen, and crawled behind a different nest block but this one didn’t carry a prey.
The wooden nest blocks decay quit rapidly in the weather and need to be replaced after a few years. However since I have made already two observations of wasps creating their own nest holes in the decaying wood instead of using the artificial drill holes I will leave the blocks to decay further so hopefully they can serve as nesting location for more wasps.
A day earlier I observed this female Ectemnius cephalotes on the bee hotel, similar to a week earlier, see here. Potentially the prey carrying wasp was the same species.
References1 Nederlands Soortenregister