Robbers

Bees are thieving blighters. Given the choice between visiting flowers and collecting nectar to make honey, or simply stealing someone else's, they'll opt for thieving every time.
Sometimes a little colony of bees can be completely overpowered by robbers who will take every last drop of honey and leave the small colony to starve. In strong colonies guard bees will fight off potential robbers but in a little colony there may be insufficient guards, especially if the entrance hole is too wide. So beekeepers keep the entrance to small colonies very narrow so that potential intruders can be more easily challenged.
However sometimes robbers just get lucky and they find an abandoned hive where a colony has died out leaving lots of unguarded honey. Never creatures to miss a free lunch, the robbers generously sample the bounty before returning home to tell their friends and relations.The news about the 'free honey' causes huge excitement in the colony and within 20 minutes 100's of bees will have descended on the source and will be busy carrying the booty home.
All of which goes to explain those bees swarming around that bait hive in my last post.There must have been traces of honey in the comb used to make up the bait hive so when the scout bees reported back to base about a potential new residence nobody paid attention (as usual) until someone mentioned the free honey...
I got some more bees nevertheless. My beekeeping buddy was so embarrassed about mistaking robbers for a natural swarm that he gave me some of his!