In beekeeping the queen excluder is a selective barrier inside the beehive that allows worker bees but not the larger queens and drones to traverse the barrier. The queen excluder is either a sheet of perforated metal or plastic or a wire grid in a frame. The openings should be limited to 0.163 inch (4.14 mm). The intent of the queen excluder is to limit the queen's access to the honey supers. If the queen lays eggs in the honey supers and a brood develops it is difficult to harvest a clean honey product and it makes fall management more difficult.
Queen excluders must be removed in the fall otherwise the queen will not be able to move with the winter cluster and will die from exposure. The death of the queen in winter will doom the hive unless the beekeeper introduces a new queen in the spring.