The queen excluder is an important part of the modern honey bee hive used to separate the brood nest area from the stored honey. The device is simply a sheet of metal or plastic with openings sized to allow worker bees to pass through but block the larger drones and queen bees. A queen excluder is typically placed above the hive bodies that hold the brood nest. As many surplus honey supers are then placed above the brood nest as are needed to store the colony’s honey. The use of queen excluders offers several advantages to the beekeeper. First, with no brood being reared in the frames devoted to honey production, the honey is clean and free of eggs and larvae. The absence of brood in the honey supers means that there is little protein being deposited in the supers. The protein comes from pollen used to feed the larvae and from silk cocoons spun by pupae. It is protein that attracts hive scavengers like wax moths. Frames of beeswax honeycomb from honey production can usually be stored over winter without chemical treatments. They merely need ventilation. Frames that held brood are often damaged by wax moth larvae while in storage. Some beekeepers prefer to not use queen excluders; they even call them “honey excluders.” They feel that the bees produce more honey without a queen excluder in the hive. However, bees can easily be encouraged to move through the queen excluder to store honey in the supers by “priming” the super with a frame containing honey or even with frames of drawn comb.
Today, I found an "upside-down" hive, a rather rare occurrence. The brood was above the queen excluder; the honey below. When the colony superseded itself, the new queen made its mating flights. When she returned to the hive, the queen, still quite small, was able to pass through the mesh of the queen excluder. I moved the queen and the brood down below the queen excluder.