When a honey bee colony becomes over crowded and conditions are right the colony splits in two in a process called swarming. The queen along with a large number of worker bees leave the original hive to establish a new one, leaving the old hive with a new queen just about to hatch. The swarm, which may contain 10,000 to 50,000 bees (usually about 20-30,000) flies from the hive and settles near by in a large cluster of bees.
Over the next few hours or days the swarm sends out scouts to find a new suitable location to build a new hive. This may be in any suitable size space whether its a hollow tree or more problematically in the wall cavity of a house.
Swarms are often heard before they are seen as a cloud of 30,000 bees makes quite a noise! Once settled the bees are very quite.
This is the best time to capture the bees.
If you need me to remove a swarm for you call right away (207) 299 6948