Swarming is a natural instinct of honeybees to perpetuate the species. Before they swarm honeybees engorge with honey and leave the existing hive in search of a new home. The swarm will cluster on tree branches and man made things like umbrellas, cars, plant pots, etc...The cluster rarely sets up shop at this location. Usually a swarm cluster remains from 1-3 days on average. If one observes the cluster, scout bees can be seen coming and going. Their job is to locate that new home. Once the spot is picked, the bees will all leave together enmass, including the queen.