We think we don't have a queen in two of our hives. We can't find her in either and little to no brood. If we introduce a new queen and we just missed seeing the old queen and she still exists what happens? Do they just fight to the death or do the worker bees kill the new queen as soon as they free her from the cage? thanks for the help!!
They kill the intruder.
Look for cells with 1 egg standing in the bottom. If you have any, even a very few, she is in there.
As Iddee said, you should look for eggs. If you don't find any, you can add a frame containing eggs to see if the bees start queen cells. That would be an indication that you have no queen and you could introduce a new one... or let the bees make their own.
You are in Mississippi so I wonder if you are in a dearth now. Queens will often reduce laying in a dearth. It's a good characteristic to have in your bees.
I agree with FRAMEshift, the queens can shut down when conditions warrent. If you are seeing any eggs at all, or even very small larvae, then have patience. It's hard, I know.
As for the queen, I had one in a hive that I didn't see for over two months worth of inspections. When the weather finally got good enough that it was safe to leave the hive open for a bit, I found her lodged between the wax and the side bar of the frame. I mean, really, what queen just sits in that spot? But apparently, that was her "go to" spot when the hive was being opened. Once I found her, she was there every inpsection for the rest of the summer.
Other indications are the behavior of the bees. Are they leaving the brood areas open for the queen to resume her job? Or are they backfilling with nectar when there are other places to put it? Just another indicator....