Yesterday I caught a hive in mid-swarm. The air and front of the hive was full of bees and there were masses on the ground. I was watching all this activity when I spotted the queen running around amidst the bees on the ground. I caught her and a few bees in a jar. I transferred her to a queen cage. By this time the swarm had settled high in a birch across the street. I put the queen and a frame of brood and bees from the hive into a new hive with undrawn foundation.
The swarm has since disappeared. I'm curious as to what may have or may yet happen. Will the swarm continue without a queen? Could there have been another queen associated with the swarm? Could they return when the excitement dies down and they discover they are queenless?