That reminded me - a couple of checkups/inspection ago I encountered a bumble, doing whatever bumbles do, inside a hive completely unmolested, it buzzed off during the course of my manipulations.In my observation, robbing bees seem a bigger threat to bees than robbing wasps. The wasps give in when (as they always are) challenged. The robber bees put up a fight when a few of them arrive at the same time. The tussles with bumbles are the most entertaining.