The queen excluder separates the brood nest from the supers. The openings let workers through but stop the queen.

What it is for

• No brood in the harvest: Super frames stay clean and are easier to extract
• The brood nest stays defined and is therefore easier to assess
• In queen rearing: It keeps the queen out of the section holding the cells

The cost

The excluder costs some throughput. Bees must squeeze through, which slows storage during a strong flow.

Some beekeepers therefore work without one and accept a little brood in the lowest super; the frames are then checked at harvest.

Materials

• Plastic: Cheap and light; the edges of the openings can be sharp and damage wings
• Wire in a wooden frame: Round wires give a smoother passage; more durable and better for the bees

The difference is noticeable: an excluder with sharp edges wears the wing margins of the foragers.

Placement

• Lay it flat; a warped excluder leaves gaps the queen passes through
• Note the orientation with wire excluders; the wires should run across the frames
• Check the queen is not already above it before fitting

Other uses

• When making a nuc: To prevent the queen going along
• When introducing: To keep a colony partly queenright
• On the floor during transport, so the queen cannot leave

Maintenance

Propolis is scraped off; a propolised excluder lets nothing through. Chilling makes propolis brittle and scraping easier.

When to remove

At wintering. The cluster moves upward, and an excluder can leave the queen behind while the bees move on — with loss of the colony as the result.