This question popped into my head and I thought I would ask BEFORE it happens to me. If a hive with a SBB is being robbed, do you close off the bottom? Would the open screen be perceived as an entrance, and would guard bees be dispersed trying to defend it?
I have SBB and have had robing. I reduce the main entrance to where only 1 or 2 bees can fit through it. I do nothing to the screen on the SBB. The robing subsides.
I do not know what the guard bees do on the screen. But they continue to block the reduced entrance.