Can I just seal the entrance to the hive and stop the bees from getting in?
Honey bees store enough up food (honey and pollen) in their hive to sustain them through long periods of time when there is little forage available (like winter). If a hive is sealed up they will continue to live off their stores, possibly for months. During this time they will be searching for another way to get out, possibly exiting through an indoor light fixture or other inconvenient place.
