Towards the end of June my Dad found a swarm of bees covering the inside and outside of a saw horse just in front of our hives. We found out that they had created some supersede Queen cells and while two hatched (rarely will two survive as they usually have a royal war to the death and the prevailing Queen wins her reign!) two seemed to survive. On this rare occasion, a second queen may have hatched at just the right time and smelled the first Queen thinking "Yikes I gotta get outta here cause there's another Queen in here!" She then left the hive with a large group of bees. This is what we suspect happened to our hive as both hives now have working Queens. But of course we are still beginner beekeepers, so it's our best guess.
A note about swarms, bees are very docile when in a swarm and the Queen is being guarded in the centre of it. They are docile because they are trying to conserve energy as they have left all of their honey reserves and have full bellies for the journey. Consider it like a family meeting where some bees fly away in search of a new home and return to report their findings. Once a bee finds a new home they will let the rest of the swarm know and away they will all fly. A swarm can stay anywhere from 40 minutes to 4 hours to overnight etc. It is hard to predict as we don't speak buzz.
When you spot a swarm, please contact the Calgary Beekeeping Association (http://www.calgarybeekeepers.com/swarmcatchers.html) as our association has a swarm catcher group that will happily come out and take your swarm away. It means they get a new hive of honey producers!
Luckily my Dad saw ours before they flew away! So my husband and I went out and swept them into pots and dumped them back in the box that you see in the photo. Unfortunately, I only took photos after we had already put about 3/4 of the bees back in the box. Once you get the Queen in the box, the rest of the bees will follow. You can see them walking in a line towards the box in this photo. Long live the Queen!