Every year the Lathyrus plants (Lathyrus latifolius) in the garden attract these bees in large numbers. The bees are also found on the bee hotels in which they take shelter and breed1. I have not been able to observe breeding in the hotel yet.
The bees on the photo’s are males roaming around and sheltering in the hotel.
More males that seem to enjoy to hang around and inside the bee hotels.
References1 Breugel, P. van 2014. Gasten van bijenhotels. – EIS Kenniscentrum Insecten en andere ongewervelden & Naturalis Biodiversity Center, Leiden.