Lesson 14: How a Colony Survives Winter

The winter cluster, and what the bees need to make it to spring

Wasp and bumble bee colonies die off each fall, leaving only new queens to start over in spring. Honey bee colonies are different: they live year after year. Because of that, most of what a colony does all year is aimed at getting through the next winter. Knowing how they do it tells you what to check before winter comes (lesson 52).

Getting ready: the bees prepare themselves

After the swarm season, colonies switch to storing honey and pollen. By late summer a healthy colony has a core of brood with pollen around it and capped honey around that, the same brood-pollen-honey pattern you learned in lesson 9, now built up as insulation and food for winter.

In fall:

• the colony raises fewer bees;
• drones are pushed out of the hive;
• the workers raised now are winter bees, which live 4 to 6 months instead of the 4 to 6 weeks of summer bees (lesson 8).

The winter cluster

As temperatures drop (bees start clustering at around 64°F), the bees form a tight ball, called the cluster, around the queen. The bees on the outside pack together like an insulating shell, and the bees inside make heat by working their flight muscles. The center of the cluster stays at about 95°F whenever there's brood, even when it's freezing outside.

The bees don't heat the whole hive, only the cluster. The rest of the box can be as cold as the outdoors.

Eating their way up

A wintering colony lives on the honey and pollen it stored:

• In autumn the bees gather in the lower part of the nest.
• Through the winter the cluster moves slowly upward as a unit, eating the honey above and beside it.
• Food has to be right next to the cluster. In very cold weather a cluster can't break apart to reach honey a few frames away, and bees can starve with honey still in the hive.

This upward movement is why beekeepers remove queen excluders before winter: otherwise the cluster can move up through the excluder and leave the queen stranded below it (lesson 52).

Brood starts again in midwinter

In midwinter, as the days start getting longer, the queen begins laying again in the center of the cluster, and brood rearing picks up quickly once fresh pollen is available.

That creates the most dangerous time of the year for food: late winter, when the colony is feeding growing brood from its stores but flowers aren't yet producing nectar and pollen. Stores can fall dangerously low at exactly this point. Checking food in late winter, and feeding if needed, is one of the most important jobs of the year (lesson 39). Your Seasonal Guide says when late winter is in your area.

What helps a colony survive

• Enough food. Lack of food is one of the leading causes of winter colony death. How much honey a colony needs depends a lot on how long and cold your winter is; the Seasonal Guide gives the target for your area.
• Enough bees. A colony needs enough bees to make and hold heat. One university guide puts 25,000 to 30,000 bees as a good size for cold winters, and says colonies with fewer than 15,000 are unlikely to survive hard freezes, though they may make it where winters are mild.
• A good queen. A colony entering winter with a spotty brood pattern often doesn't survive.
• Low mite levels. With little brood in winter, mites feed on the adult winter bees, weakening them and shortening their lives, and viruses often follow. Colonies that go into winter with high mite levels often don't make it (lessons 54–56).
• Shelter from wind, but with airflow, so moisture doesn't build up inside the hive.
• Protection from mice, which move into hives looking for warmth.

Leave them alone

Once winter sets in, the best thing you can do is disturb the colony as little as possible. Opening a hive breaks the cluster's warmth. If you must look, keep it brief and do it only on a mild day. (Guides differ on the cut-off: some say no inspections below 45°F, others 50°F. Your Seasonal Guide uses the local weather check.)

What to remember

• Honey bee colonies live year after year; almost everything they do aims at surviving winter.
• In cold weather bees form a cluster that keeps its center at about 95°F when brood is present; they heat only the cluster.
• The cluster moves up through its stores; food must be next to the cluster.
• Late winter is the danger time for starvation: brood rearing starts before flowers do.
• Survival needs food, enough bees, a good queen, low mites, shelter and dryness, and very little disturbance.

Quick check

1. Why can a colony starve even when there's honey in the hive?
2. When is the riskiest time of year for running out of food, and why?
3. Why take queen excluders off before winter?

Show answers

1. In the cold, the cluster can't break up to reach honey that isn't right next to it. 2. Late winter: the queen starts laying and brood is fed from stores before flowers produce nectar and pollen. 3. The cluster moves upward through the winter and can leave the queen stranded below the excluder.

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Adapted from: UF/IFAS Extension, Overwintering Honey Bee Colonies in Northern Climates (ENY-161/IN1006) and Welcome to the Apiary! (4H446); UGA Bee Program, Getting Started: Honey Bee Biology and Honey Bee Management; Delaplane, K. S., Honey Bees and Beekeeping (UGA Extension Bulletin 1045, rev. 2017); Mississippi State University Extension, Beginning Beekeeping in Mississippi (P3594); University of Arkansas, Complete Beekeeping Short Course, Part 4.

Adapted from university Extension sources. Experienced Georgia beekeepers are reviewing these lessons. See something that doesn't match your experience? Tell us.