When signs of swarming are apparent, consider using the Swarm Bandit.
This creative product can save you from having to climb trees to retrieve a swarm that has left the hive.
When swarming occurs, the queen becomes trapped inside the ventilated compartment, preventing her from leaving the hive. Slide the reducer to trap the swarm. Then remove the hive, place into the entrance of an empty hive and open the reducer to allow the swarm to flow into their new home.
A frame of brood will encourage them into their new hive and give them a jump start.