Robbing Honey Stores
Wasps like honey, and they will steal given the chance. A strong colony will defend itself by ganging up on the robbers, even though bees will die after stinging an invader, and wasps can sting again and again. A strong colony has the home court advantage and will generally convince invading wasps to move along. Beekeepers know that bees themselves are not above theft from time to time, and sometimes bees will attempt to rob honey from other hives, which can quickly weaken the robbed colony.
Attacking Weak Colonies
Weak bee colonies are susceptible to destruction in the event of a sustained attack by some wasps. Asian giant hornets and yellow jackets can be extremely aggressive, and will wage relentless attacks against a weakened colony, eating both the honey and the dead bees. Beekeepers will sometimes augment a struggling colony with wasp traps. These traps are distributed liberally throughout the area around the hives, using non-sweet bait, like meat or dog food, to avoid trapping bees.
Stinging Beekeepers
Bees are accustomed to their keepers and have a generally non-aggressive temperament. Many beekeepers don't even wear protective clothing while they are tending hives. But beekeepers also plant or co-locate with the same kinds of colorful pollinators that bees like to ensure there is adequate pollen for honey production. The problem is that many wasps are attracted by the same plants for the nectar, and an unprotected beekeeper runs the risk of being stung by some of the bee's more aggressive cousins.
Eating Bees
Bees like pollen, and wasps like a drink of nectar from many of the same plants. But wasps are not vegetarians. That nectar may be washing down whatever insect last fell prey to the wasp. Wasps also like human food, especially fish and meat. If there is garbage near the hive, this can quickly attract pack hunter wasps like yellow jackets, which will unhesitatingly capture, kill, dismember and eat individual bees that they encounter.