When a hive gets too big the queen and about half of the bees in a colony leave to find a new home. This usually happens in spring and early summer. The bees cluster around the queen and cling together, usually on a tree branch. These bees are fairly docile because they have no hive to defend.
Bees are opportunistic when looking for a new home. A cavity in a hollow tree is their natural home but houses and barns also make great bee homes.
Removal of bees from a building requires removing siding, capturing the bees. and hopefully the queen. All of the honey comb, honey and brood comb must be removed to avoid bug infestations.
Are you sure you have Honey Bees?