Queen excluder

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. Queen excluders are also used with some queen breeding methods. Some beekeepers believe that excluders lead to less efficient hives.

Typically, the queen excluder is either a sheet of perforated metal or plastic or a wire grid in a frame with openings are limited to 0.163 inches (4.1 mm). 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.

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.

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.

Some beekeepers believe that queen excluders result in less efficient movement for worker bees, and therefore prefer not to use queen excluders, but rather to control the location of the queen by other methods. This belief is based on the observation that the bees tend to be less prone to move up the hive into the supers when a queen excluder is used, preferring to fill cells in the brood box with nectar and honey first. This behaviour constrains the size of the brood nest which the queen can lay eggs in, which has two effects on the colony: the buildup rate of workers is constrained and a dearth of space for the queen to lay can lead to swarm preparations.

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