Yesterday while I was going through my hive I noticed an empty swarm cell on one of the bottom frames in the lower brood chamber. Does this mean that the old queen has been replaced? About four days ago I did notice an unusually large number of bees around the entrance to the hive and in the air above, but it did not seem to be a coordinated "swarm". This is my first year at this and I have never seen an actual swarm before. The hive seems to have just as many bees as it did two weeks ago. I did not see the queen during my inspection - but with so many bees it's not surprising. Should I be concerned with these two factors? And what exactly does a swarm look like? Thank you in advance for any comments.