Hive #4 is missing a queen. I knew something was wrong when I look at all the hives and this one has the least activity. You kinda get a feel for what's happening and how each hive works when you can look at them several times a day - they're at the end of my garden so when I'm outside it's easy to see.
So I opened the hive yesterday and sure enough, no sign of a queen and no brood. But lots of open queen cells - maybe 6 or more. I decided to leave well enough alone and hope they make their own queen. I'll open the hive in about two weeks. I can look at the front of the hive and see if they're bringing in pollen - that's a sure sign of a queen in the hive. There's lots of bees in the hive and drones. Again, don't know what happened to the queen.