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 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.
Queen excluders are removed in the autumn; otherwise, the queen would not be able to move with the winter cluster and would die from exposure. The death of the queen in winter would doom the hive unless the beekeeper introduces a new queen in the spring.
Some beekeepers believe that queen excluders result in less efficient movement for workers bees, and therefore prefer not to use queen excluders, but rather to control the location of the queen by other methods.
Queen excluders are used with some queen breeding methods, especially as a way to allow queen cells to be built in the same hive with an existing queen, or as a way to house multiple queens in the same hive.[1] Queen excluders can also be constructed of hardware cloth screen, of which #5 Hardware Cloth is often cited in references as sufficient for allowing worker bees to pass, but not queens.