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 is food grade plastic . The openings are limited to 0.163 inches (4.1 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.