So, my bees swarmed today. That was an adventure. My friend and I were able to retrieve the swarm from pretty high up in a tree on my property. Bees will swarm when a hive decides to split, usually because the space they're living in is getting too cramped for the number of bees that the local resources can support. In this case it's because we hadn't added additional boxes to expand the space for the hive soon enough, oops.