Mating Nuclei

A mating nucleus (mating box, mini nuc) is a small hive set up with a small number of bees so that a young queen emerging from a ripe queen cell can make her mating flights and start laying. The aim is to mate as many queens as possible, safely, with as few bees and as little equipment as possible; but the smaller the box, the greater the risk of starvation, overheating, absconding and robbing. This page covers the types of boxes, how to choose one, setting up, placement, management and reusing boxes throughout the season.

What is a mating nucleus used for?

Giving a ripe queen cell directly to a large colony means leaving one colony broodless for weeks for every queen. A mating nucleus reduces that burden: a small community of a few hundred young bees receives the queen, feeds her, accepts her back after her mating flights and tends her first eggs. Once the queen starts laying she is removed and assessed, and the box is given a new queen cell.

This makes the mating nucleus the piece of equipment that sets the capacity of queen rearing: how many queens you can produce per week depends largely on how many working boxes you have.

What types of mating nuclei are there?

What should you look for when choosing a mating nucleus?

• Frame compatibility: If the box takes the same frames as your standard hive (as with divided boxes and nucs), adding brood and bees is easier. The small frames of mini boxes are a separate system.
• Feeder: A feeder compartment that can be filled from inside and in which bees cannot drown is essential in mini boxes; it holds fondant or thick syrup.
• Ventilation: A screened ventilation opening for the days the box is kept closed; in hot regions this directly prevents bee losses.
• Entrance slide: A slide that closes the entrance completely, reduces it and, if needed, closes it with an excluder (blocking queens or drones).
• Insulation: Foam boxes soften temperature swings; thin wooden boxes heat up quickly in the sun.
• Transport and durability: Low weight, a lid lock and a washable surface; foam boxes are easily damaged by birds and rodents.

How do you set up a mating nucleus?

1. Collect bees: Young bees are shaken from the honey super or from open brood frames of a healthy, strong colony; make sure the queen is not taken. Young bees are less likely to abandon the box.
2. Fill the box: A handful of bees is enough for mini boxes; nucs are given bees together with frames of sealed brood, honey and pollen. Starter strips of foundation are fitted to the frames of mini boxes so the bees can draw comb.
3. Feed: The feeder is filled. Divided boxes and nucs should contain a frame of honey and pollen.
4. Keep them in the dark: Mini boxes are kept with their entrances closed in a cool, dark place for a few hours to a day; the bees sense they are queenless and cluster together.
5. Introduce the queen cell or virgin queen: A ripe queen cell (day 10 after grafting) is placed upright, or a virgin queen is introduced in a cage.
6. Move into place and open: The box is taken to the mating site and the entrance is opened in the late afternoon. For boxes set up close to the source hive, extra bees are added because foragers will return to their old location, or the box is moved a few kilometres away.

How should mating boxes be placed in the apiary?

A large share of queen losses happens when a queen returning from her mating flight enters the wrong box and is killed, or is taken by birds. The layout of the boxes directly affects this loss:

• Different directions: Face the boxes or compartment entrances in different directions.
• Colour and shape: Put different colours and patterns (circle, triangle, stripe) around the entrances.
• Avoid straight rows: Do not line up identical-looking boxes in long straight rows; use groups, circles or irregular spacing.
• Single-post stand: Setting boxes on separate posts or stakes both creates differences in orientation and protects against ants.
• Shade: A small box in the midday sun heats up quickly; partial shade is preferred.

Management and checks during the mating period

• Emergence check: 2–3 days after the queen cell is given, a cell with a neatly opened tip shows the queen has emerged.
• Quiet period: The queen usually starts flying at 5–7 days old. Do not open the box during this period, especially during the afternoon flight hours.
• Egg check: Look for eggs about 10–14 days after emergence; if the weather has been poor, it takes longer.
• Feeder: Check the feeder at every visit; when the nectar flow stops, mini boxes can starve within a few days.
• Robbing and absconding: Keep the entrance narrow. In mini boxes the bees may abscond together with the virgin queen; plenty of young bees and enough food reduce this risk.

How are mating boxes reused through the season?

After the laying queen is removed, the cycle continues by giving the box a new ripe queen cell. Because the box contains open brood left by the queen, the bees readily accept the new cell; however, always check that they have not started emergency queen cells from that brood.

• Boosting strength: After a few cycles the bees in a mini box age and dwindle; add young bees or a piece of sealed brood.
• Overcrowding: If the queen stays in the box too long, a mini box fills up quickly and the bees may leave in a swarm-like way; remove the queen on time.
• End of season: Nucs and stackable mini hives can be strengthened and prepared for winter; mini boxes are usually combined and their bees given to large colonies.
• Cleaning: Empty boxes are scraped, washed, dried and stored indoors. Boxes in which disease was seen are not moved to other colonies.