A substance looking like sawdust was found at the base of a Populus tremula tree, seemingly coning out of a developing tree hollow, which was too small for the Pteromys volans we were looking for. Daniel Ferneyhough poked into the sawdust-filled hollow, and, together with more sawdust, this Hymenopteran (Aculeata) fell out. Soon, 4 to 5 Hymenopterans were buzzing around. On this day, the maximum temperature was 3.5 degrees Celsius; the observation was made in the early afternoon.