I always wrap everything tightly with duct tape until I get home. I've been present for dozens and dozens of swarms and each and every one is as thrilling as the last. I keep a close eye on the hives toward evening. When evening comes and you see bees clinging in unusual numbers on the front of the hive, chances are it is getting ready to swarm. Swarming usually happens in the morning, so I try to check on each of the possible swarming hives and cross my fingers.
Swarms start as a great retreat from the hive and at a massive rate.
You will see the honeybees literally bubble out of the entrance as if they were frantically escaping a fire. They immediately take flight and follow the scout bees toward either the permanent home or a local stop-over spot. As they lift from the hive entrance and rise to the sky, the bees make a massive humming sound that can be heard for hundreds of feet. This humming keeps just about every bird or insect away. The last swarm I watched was amazing.