Yesterday around 4PM I noticed a lot of activity in front of the Brown Hive, and a little bit less in the Green Hive. It looked like orienteering flights on steroids - there were many bees flying around the entrance. It looks like it may have been a swarm, but I watched for a few minutes but didn't see any bees making for the trees. They all seemed to fly out about 20-30 feet away from the hive, and that's it. But there were a lot of them!
I thought it might have been robbing, but I didn't see bees making mad dashes to the hives (last year I had my brown hive robbing out one of my weak hives).
So it could have been a swarm. But I spent a lot of time looking in the tree tops and didn't see anything. Within about an hour, the traffic was normal. Strange!
Today I went into the Brown Hive to see evidence of a swarm. You know you had a swam because you see capped queen cells, and you see fewer bees. I saw neither. I also saw frames of good brood:
Other frames had very young larvae on them as well (I thought a few days before a swarm the queen stops laying).
Looking at this hive, I wouldn't expect anything amiss. If it did swarm, then there isn't a laying queen, and I should see next week the absence of young larvae.
According to the bee math, there won't be any new eggs until about 20 days if this swarmed. I'll check next week and see.