Queen Excluder

A queen excluder is a dividing panel placed between the brood box and the honey super, with gaps that worker bees can pass through but the larger-bodied queen and the drones cannot. Its purpose is to keep the queen laying in the brood box and leave the super free of brood. Used at the right time and in the right colony, it makes harvesting easier; used wrongly, it can leave the honey super empty.

What does a queen excluder do?

The basic logic of the excluder rests on the difference in body size between bees: a worker's thorax passes through the gap in the excluder, the queen's does not. This simple separation gives the beekeeper several important benefits:

• Brood-free supers: there is no brood in the frames being harvested; larvae and pupae don't get mixed into the honey during extraction.
• Light-coloured comb: comb in which brood has never been reared doesn't build up cocoon remnants and stays light-coloured; super combs can be used for years.
• Finding the queen is easier: the search area is limited to the brood box.
• Planned harvesting: honey supers can be removed without disturbing the brood box; used together with a clearer board, it works much more efficiently.
• Management techniques: used to keep the queen in a particular section in practices such as swarm prevention, queen rearing and brood breaks.

What are the drawbacks of a queen excluder?

The excluder is a controversial tool; some beekeepers call it a "honey excluder", because when used wrongly it slows the passage into the honey super. The known drawbacks:

• Resistance to passage: bees may be reluctant to go up through the excluder; especially in a weak colony and with a super of undrawn foundation, the honey super may stay empty, and the bees may fill the brood box with honey and go into swarming mode.
• The drone problem: drones left in the super cannot get down to the entrance and die on top of the excluder. In a hive without an upper entrance, this build-up can clog the excluder.
• Risk of splitting the winter cluster: if the excluder is left in the hive over winter, as the cluster moves up towards the honey the queen may be left below the excluder and freeze to death.
• Propolis and wax: an excluder that gets clogged over time makes passage even harder.
• Wear on wings and hair: excluders with sharp or burred edges can wear down workers that pass through frequently.

When should a queen excluder be fitted?

Timing is the most important factor in whether the excluder will work.

1. The colony must be strong: the brood box should be full of bees, with most frames covered in brood and stores.
2. The nectar flow must have started: an excluder fitted before the honey flow begins is seen by the bees as an obstacle and delays the move into the honey super.
3. Make sure the queen is below: before fitting the excluder, the queen should be seen, or at least the frames moved up into the super should be checked for eggs. Otherwise you will trap the queen in the super.
4. Harvest and autumn: when the last honey super is removed, the excluder comes out too, and the colony goes into winter without an excluder.

Practices that make the excluder easier to use

• Start with drawn comb: give the first super of foundation without an excluder; once the bees have started drawing it, put the excluder in between.
• Open an upper entrance: opening a small upper entrance into the honey super lets foragers carry honey up without passing through the excluder, and lets drones get out.
• Keep it clean: replace and clean an excluder clogged with propolis and wax.
• Seat it fully: a gap of a few millimetres at the edge is enough for the queen to get up into the super.

Management techniques using a queen excluder

Swarm prevention and rearranging the brood nest

In strong colonies showing a tendency to swarm, some of the brood frames can be moved above the excluder while the queen is kept in a box below. This opens up laying space in the brood box and reduces congestion in the hive. A well-known form of this approach is called the Demaree method. In practice, the brood frames above the excluder should be checked for queen cells a few days later and the cells destroyed if they are not wanted.

Queen rearing and splits

Beekeepers who rear queens separate the section containing the cell bar frame with an excluder to stop the queen damaging the cells. An excluder can also be used when making a new split to guarantee which side the queen ends up on.

Brood breaks

In varroa control, brood rearing can be halted temporarily by confining the queen with an excluder to a section of a few frames or to a cage. Such practices should be planned and not left in place longer than intended.

Is it possible to work without an excluder?

Yes. Many experienced beekeepers don't use an excluder. The queen usually goes up into the super very little; she especially prefers not to move upwards if there is a band of full honey (honey arch) above the brood box. The advantage of working without an excluder is faster movement into the honey super and less intervention; the disadvantage is having to check every frame for brood at harvest time. If a brood frame turns up in a honey super, it is moved back down to the brood box and never extracted.

When should a queen excluder not be used?

• In winter and during winter preparation,
• in weak or newly established colonies,
• on a first super given only foundation, not yet drawn,
• when there is no nectar flow, or it has stopped,
• when the queen's whereabouts are unknown.

Common mistakes

• Accidentally leaving the queen above the excluder: if you see eggs in the super a few days later, the queen is upstairs.
• Forgetting the excluder in the hive over winter.
• Continuing to use an excluder that is warped, holed or has widened wire gaps.
• Fitting an excluder meant for a different hive type so that gaps are left at the edges.
• Thinking the excluder is a part that "increases honey yield": the excluder's job is to separate brood and honey, not to increase the amount of honey.