What do you do if a swarm of bees attack?

If you really have a swarm of bees -- a football-sized cluster of bees hanging from a tree branch or something similar -- the best thing to do is contact a local beekeeper who will be glad to come and collect them. If you do nothing, they will be there anything between a couple of hours and a day then will move on, either to another post, or to a new home. Bees in a swarm are usually quite docile because they have no hive to protect and they fed well before they left their old hive. However, it is better not to disturb the swarm in any way.