this happened to my neighbors and I am curious to know what might have happened.
A few days ago one of their hives swarmed. This hive had a marked queen in it and it's from a package installed in May. They saw the swarm come out and land on a nearby tree. They collected it in a cardboard box, which then they put on top of a hive, but they did not look for the queen then. Given that the old queen leaves with the swarm it should have been the marked one.
Two days later the same bees swarm again out of the new box (so not the hive that swarmed the first time, but the actual swarm). I guess the technical term is they "esconced" since they left the hive. They captured it again (they went to the same branch) and put it back. This time they found the queen and it was not marked.
What might have happened? The fact that the queen is not marked leads me to believe that this is not the first time that hive swarmed. But why would the swarm, leave again after a couple of days? I should add that these neighbors are very good at working the hives, and checking them every 2 weeks and they had seen no sign of swarming so far (and I assumed they had seen the marked queen every time).