Put your ear against the wall, and listen for buzzing. If there are bees in the wall you can make a very small hole in the wall (nail size) and spray a fogger in that will kill the bees.
You need to hire a professional Bee Removal Company. I actually had this problem. A man came to my home. Suited up in protective gear. He first had to break through the wall. Then after killing the...
When faced with this problem, it is best and safest to employ a professional beekeeper to rid the house of the bees. If this is not possible, then I would suggest searching for the correct formula...
NOTE: YOU TRY THIS AT OUR OWN RISK. First of all, it's much more likely a wasp's nest than a bee's nest. Bees do not nest in that way. Note that is is not a terribly "environmentally conscious" way...
Most likely you will never see the queen bee. She is under guard deep in the hive. If you happen to destroy the hive to find her, she will be a large distorted bee with most of her body being a giant...