Yes, yeloww jacks can be predators. They search for both, sugars and meat. Sugars are the principal food for adults and proteins for larvae. Wasps can enter hives and steal honey when colonies are weak to cover all the stores when weather is cold. They fly round the hives searching for any dead or weak honey bee (worker or drone) which they kill and cut into portions. Those parts of the bee body containing muscles (thorax) are then brought to wasp nests and fed to larvae. This activity would not be dangerous for bee colonies. On the opposite this is an useful sanitary cleaning of the nearest vicinity of hives. But if there is not this kind of prey enough larger species of vasps (Vespa, Vespula) attack honey bees at the hive entrances and kill them. In the battle between bee and wasp the latter usually is the victor. It cannot be excluded that wasp can transfer bee diseases among hives.