These honeybees are swarming. Especially after a warm winter, hives can become overcrowded. At that point, the queen lays eggs for a new queen. About half of the worker bees will gorge themselves on honey, to keep them going as they search for a new home. They also stop feeding the old queen, so she will lose enough weight to be able to fly to a new location.

When the time comes, the old queen and the honey-stuffed workers leave the hive. The queen will fly to a tree, where the workers cluster around her. A number of the best foragers are sent out as scouts, looking for a new home. As the scouts return, they perform a dance, similar to the dance used to indicate the location and quality of food sources. Other scouts check out the most promising locations, until enough agree for the swarm to move into their new home.

Experienced beekeepers anticipate swarming, and move the old queen into a new hive. This swarm may be feral bees, or it may be a swarm from a beekeeper who was not watching close enough.