Yep that is what happened two Saturday s ago, I was introducing a scout from Troop 106 , and his dad, to the concept of beekeeping, and we walked up and saw a very small bundle of bees in the grass.
I poked around a bit and found a queen, very neat !! Had to run up to the house to get my bee box and queen clip, and returned in time to easily catch her.
Left the clip on the ground with other bees while I prepared a nuc for her. Took but 3 minutes before 5-6000 bees were flying above us. Very cool feeling, and the sound was amazing . And within 5 minutes they had calmed down and started to walk back into the hive.....nothing to see here, move along now.
So we caught a swarm before it swarmed, neat! Also discovered that one of my Wayne's hives seems to have lost their queen too, and had been overrun with Slimy damn larvae of SHB. Lost about 6 frames so far. Took them out into the sun about 50 ft away and let the bees take can of them. Will pull the honey supers before they get infected too.
Such is beekeeping, Win one, lose a bigger one.
The beekeeping books have been returned from the printers, they look fantastic.