Systems are offered for heating a hive from outside. With honey bees the application is limited and the necessity rare.

What the colony does itself

A colony regulates its own temperature. It warms by vibrating the flight muscles and holds the brood nest around thirty-five degrees — very precisely.

In winter it forms a cluster whose interior stays warm. Cold is not a problem for a healthy colony with adequate stores.

Why colonies die in winter anyway

Rarely from cold. The usual causes are:

• Varroa and the viruses it transmits
• Unreachable stores — the cluster cannot move sideways in the cold
• Damp; in winter condensation kills more than cold
• Queenlessness in autumn
• Going into winter too weak

Heating solves none of these — and it can worsen the moisture problem.

Where heating is used

• Holding queen cells under controlled conditions
• Instrumental insemination and laboratory work
• Very small mating units in cold regions
• In research into hyperthermia against Varroa — a method still in development, where the margin between mite and brood is narrow

What does help in winter

• Insulation above, so the roof does not cool sharply and less condensation forms
• Ventilation that lets the moisture escape
• Restricting the space to what the colony covers
• Stores above the cluster
• A dry site and a roof that does not leak

Insulating without ventilating traps the moisture; ventilating without insulating costs the heat. The two belong together.

The practical line

What brings a colony through winter is determined in August, not in January. Heating is not an answer to a problem created months earlier.