About Swarming
Honey bees swarm as a natural means of replicating the colony and ensuring the species reproduce and survive. They swarm in response to a variety of factors, including congestion within the hive, age of the queen, amount of queen pheromone being produced, amount (or lack of ) ventilation, and natural inclination of the particular sub-species of honey bee to swarm.
When a colony swarms, roughly half the workers stay behind with at least one queen cell containing a new queen ready to emerge. The departing swarm itself includes the mother queen and about half the population of the colony. They may temporarily form a large cluster on a bush, tree branch, the side of a building, under a park bench seat, etc. While in this cluster, which may persist for minutes, hours, or even a day or two, they are generally quite docile and, if they can be reached, can be easily captured and relocated to a managed hive.
The bees generally remain in the cluster until scout bees find a suitable new permanent home. This new permanent home may be a hole in a tree, an abandoned building, or your house. Once the bees have entered their new home, they quickly build comb and begin rearing brood and storing pollen and nectar (which the bees turn into honey). Removing the bees frequently involves removing a portion of interior walls or ceilings, or removing a section of roof, soffit, or siding to expose the bees.
Should you find honey bees in your home, garage, or an outbuilding, do not spray them with pesticide. No pesticides are approved for use on honey bees, and ethical exterminators generally won’t touch honey bees. Although it’s unlikely you’d be able to reach enough of the comb to kill all the bees by spraying the entrance, if you were successful, you might create bigger problems. Without the honey bees to care for the brood and honey, vermin (ants, mice, wax moths, small hive beetles, etc.) will be attracted, and the honey may ferment and leak down walls and through ceilings, potentially causing major damage.
Contact someone experienced in removing honey bees to assist you. Most will work with you to provide the service you need, whether that be full bee extraction and structure repair, or if you’re handy and are comfortable doing repairs yourself, just removal of the bees.