Originally Posted by taltos

I went back and checked some references from when I kept bees. A better explanation than what I gave earlier is that the population outgrew its hive and the old queen and many of the workers and foragers have left the hive. This is a correction to my previous post where I stated that the swarm had a new queen. The workers will raise a new (virgin) queen from some special egg cells and by feeding the larvae special food (queen jelly). The first queen out if healthy will be allowed to sting and kill any remaining queen larvae. If the workers sense that the new queen is not 100 per cent, they will sting this queen to death and await the emergence of the next one. After the queen gains strength, she must make a mating flight where she flies high into the air and is pursued by the drones. One will catch the queen and mate with her and will promptly die. The queen only needs to mate once. The rest of the drones will die by winter and will only be replaced at the next hive division. Hope that this helps.