Grafting is the transfer of a young larva from a worker cell into a queen cup. It is the central operation of queen rearing and the one most beginners fear unnecessarily.

The critical variable: larval age

The younger the larva, the better the queen. A larva grafted late has fewer ovarioles and a shorter life.

What to look for: the smallest larvae visible, curled like a comma, lying in a clearly visible pool of brood food. If the larva fills the bottom of the cell it is already too old.

Preparation

• Know the larval age. Give the breeder colony an empty comb and note the date she lays in it
• Prepare the starter colony first. The cells must go in immediately after grafting
• Warm the cups. Cold plastic reduces acceptance
• Have strong light. This is the most useful aid there is; day-old larvae cannot be selected without it

The operation

• The tool is slid under the larva, taking the brood food with it
• The larva is laid in the cup the same way up; turning it over kills it
• It should not be pressed or dragged
• Work quickly; a larva dries out in minutes

A drop of diluted royal jelly in the base of the cup delays drying and helps acceptance.

Working conditions

• Cool, shaded and out of the wind
• Cover waiting bars with a damp cloth
• Do not work in direct sun
• Keep the room from being too dry

Larvae are killed more often by drying and chilling than by clumsy handling.

Acceptance

Acceptance is checked the day after grafting. Cells being drawn out and provisioned show it has worked.

If acceptance is poor, the causes are usually:

• The larvae were too old
• The starter colony was not strong enough or not queenless
• There was no flow and no feeding
• The cups were dirty or carried a smell
• The larvae dried out

Grafting-free systems

Systems exist in which the queen lays into removable cell bases, so the larva is never touched. They remove the skill requirement but cost more and are slower at scale.

For a beekeeper rearing a few queens a year they are a reasonable alternative.

Practice

Grafting is a manual skill and improves quickly with repetition. The first attempts usually have low acceptance; this is normal and not a reason to stop.