The mating nucleus is a small unit in which a queen emerges, mates and begins to lay. It is the last step of rearing and where most queens are lost.

The balance of size

This is the decisive point.

• Small saves bees — important, since every nucleus costs bees from a production colony
• Too small cannot hold heat and has no store buffer; in cold or wet weather the unit is lost

The right size depends on the climate: in a cool, changeable climate a larger unit is wiser than the smallest form.

What goes in

• Enough bees to keep the cell warm
• Stores, or a feeder that is topped up
• Some pollen
• A sealed cell or a newly emerged queen

When the cell goes in

Before emergence — about twelve days after grafting. If the queen emerges in the cell builder, she destroys the remaining cells.

This is why the grafting date must be written down.

The mating flight

• Mature drones must be present in the area
• The weather must permit flight; a long spell of bad weather leaves the queen unmated or poorly mated
• Do not open the unit during these days
• Raised drone brood in worker cells later means insufficient mating; such a queen is replaced

The vulnerability

Small units are most exposed to robbing, wasps, ants and birds. Bird pressure counts particularly here: a queen taken on her mating flight costs the whole unit.

• Keep the entrance very small
• Different orientations and landmarks against drifting
• Do not place among busy hives during a dearth

After mating

Once she is laying and the brood pattern is tight, the queen can be used or sold. The unit is cleaned before another cell goes in.