How do you stop honey bees swarming?

Generally yes. One or even a few wasps trying to get into a hive will easily be repelled -- and probably killed -- by the guard bees at the entrance. However, if there is a concerted attack by a lot of wasps at the same time they could overcome the guard bees and get in. If they do, they will kill as many bees as they can in order to get to the honey.