If the fog levels have risen and you harvest honey, the angry bees will fly off and you will have to collect them again! If the fog levels are low, you don't need to recapture the bees. They are perfectly happy in that case.
When there is fog in N.M.L., the bees disappear from their hives after you collect honey. That's why you have extra cans of bees; so that you can put them back in their hives if they fly off.