1. Priorities of the month

• Keep the colonies undisturbed and avoid any unnecessary opening.
• Check the apiary after wind, snow or severe weather.
• Carry out the winter varroa treatment once no capped brood remains.
• Monitor food stores without feeding systematically.
• Use the quiet period to maintain equipment and update records.

2. December at the apiary: the guiding idea of the month

Objective To understand that December is above all a month of rest for colonies, with one important health intervention that has to be timed correctly.

In December, colonies generally sit together in the winter cluster and greatly reduce their activity, but their condition depends on the climate, altitude, the course of the season and, in particular, the conditions during autumn.

The priority is not to open the hives, but to protect their quiet, to check the apiary from the outside and to identify the moment when no capped brood remains.

This window makes it possible to carry out the winter varroa treatment effectively, without automatically inferring broodlessness from the calendar alone.

With milder autumns and early winters, the brood break may become less regular and less predictable. In lowland areas, some colonies may therefore still be rearing brood while apiaries at higher altitude have already entered a pronounced winter phase.

Further reading

• Overwintering in the honey bee: a very particular phase of its biological cycle
• The winter cluster

3. Priority tasks of the month

3.1 Preserving calm and securing the apiary

Objective To prevent wind, snow, animals or repeated vibrations from unnecessarily disturbing the colonies during overwintering.

What to look at
The stability of the stands, the position of the hives and roofs, branches liable to strike the walls, damage caused by wind, snow load or animals, and the condition of rodent guards. Also check that water cannot accumulate inside or immediately in front of the hive.

Practical steps
Begin by observing the apiary as a whole from a distance, then approach the hives only where something needs to be checked specifically. After heavy snowfall, gently clear entrances blocked by compacted snow or ice. Check that the roofs remain watertight and that the hives have been neither overturned nor displaced.

Points to watch
A covering of snow around a hive is not necessarily a problem. What calls for intervention is above all a lastingly blocked entrance, moisture build-up, water ingress and repeated impacts. Do not shake the hive and do not knock on its walls to check whether the colony is alive.

When setting up an apiary, a slight forward tilt of the hive can help water and debris drain out. In December, the main point is simply to make sure that drainage remains possible: a stable hive should not be lifted or repositioned unnecessarily during cold weather.

The roof and walls should protect the colony from wind and weather without making the hive airtight. Suitable insulation can limit certain heat losses, but it replaces neither a healthy and sufficiently populous colony nor accessible food stores.

Further reading

• Successful overwintering
• Hive insulation put to the test of the bees' collective thermoregulation
• Practical Guide: 4.3 Overwintering

3.2 Observing overwintering without disturbing

Objective To identify abnormal situations from external signs, without turning every observation into a firm diagnosis.

What to look at
The state of the entrance, the amount of bee mortality in front of the hive, any faecal spotting, unusual noise from a colony, the debris visible on the varroa insert board and, where the apiary is equipped for it, changes in weight or internal temperature.

Practical steps
Compare the colonies with one another and take their history into account. A few dead bees in front of the hive or on the snow are consistent with normal winter mortality. A sudden accumulation, a lastingly blocked entrance, extensive faecal spotting or a marked change compared with previous weeks warrant closer observation.

Points to watch
Condensation, the position of the cluster under a transparent crown board, hive debris or internal temperature can provide indications of colony activity and of the possible presence of brood. None of these signs is sufficient on its own, however, to demonstrate the absence of capped brood.

Nor does apparent silence prove that the colony is dead. Before any opening, combine several observations and avoid inspections prompted by concern alone.

Further reading

• Practical Guide: 4.8.1 Entrance observation
• The fascinating secrets of reading hive debris
• Practical Guide: 4.8.2 Hive floor debris check

4. Colony health

Objective To reduce the residual varroa population effectively during the period when the mites are no longer protected beneath the brood cappings.

What to look at
The presence or absence of capped brood in each colony, how the summer treatments went, the results of previous monitoring and the general state of the apiary. December is often the month with the least brood, but some colonies may still retain some, particularly after a mild season and autumn.

Practical steps
Carry out the winter treatment with a veterinary medicine authorised in Switzerland, following the Practical Guide corresponding to the chosen method and the product leaflet. Spray treatment, trickling and oxalic acid vaporisation are subject to different conditions of use: outside temperature, personal protective equipment, equipment, dosage and procedure must all be followed strictly.

For efficacy against varroa, the decisive criterion is the absence of capped brood. The presence of open brood alone does not necessarily preclude treatment according to the current Practical Guides of the Bee Health Service.

Where opening the hive is necessary to check the brood status, keep it brief, targeted and limited to what is strictly necessary. The aim is not to carry out a full colony inspection in the middle of winter.

After the treatment, insert the varroa board if necessary and monitor the post-treatment mite drop for the period provided for in the varroa management concept. A high mite drop must be interpreted in line with the recommendations in force in order to decide whether a supplementary measure is needed.

Points to watch
Do not treat automatically because the calendar says December. External observations and sensors can guide the decision, but a brief check remains the most reliable method where doubt persists.

If a small residual area of capped brood is present, it can be removed in accordance with the recommendations of the Bee Health Service. If the area is larger, postpone the treatment briefly and check again. Where capped brood persists until the end of December, seek advice from the Bee Health Service rather than improvising late or repeated treatments.

The winter treatment reduces the residual varroa population and improves the starting conditions for the following season, but it cannot reverse damage already suffered by the winter bees. A high varroa infestation in late summer or autumn may already have weakened these bees and favoured viral infections before the winter treatment is carried out. A severely affected colony will therefore not be “cured” by a late treatment: successful overwintering is prepared several months earlier.

User protection is indispensable, particularly during oxalic acid vaporisation. Use exclusively the protective equipment, product, dosage, specified temperature range and procedure provided for in the product leaflet and in the current Swiss documentation.

Asian hornet
In December, pressure from the Asian hornet at the apiary is normally greatly reduced, but it is not necessarily completely absent as long as persistent cold has not set in. During particularly mild periods, some residual activity may still be observed. Leaf fall can also make some secondary nests more visible: observe them from a distance, photograph them and report them at frelonasiatique.ch, even when they appear abandoned. Do not act on a nest yourself; fertilised young queens leave the colonies and overwinter in sheltered places until spring.

Further reading

• Winter varroa treatment: what to do if colonies are still rearing brood?
• Practical Guide: 1.3.2. Trickling method
• Practical Guide: 1.3.3. Oxalic acid vaporisation

5. Food stores and current resources

Objective To detect a genuine risk of starvation without triggering systematic winter feeding.

What to look at
The relative weight of each hive, how it has changed since the autumn, the differences between comparable colonies and the information recorded during winter preparation. There is no universal total weight valid for all hives: the type of hive, the material, the number of boxes and the internal equipment strongly affect the reading.

Practical steps
Where it can be done without jolting, carefully heft the hive. Where experience is not yet sufficient to assess weight differences reliably, a spring balance used consistently can provide a useful comparative indication. Digital hive scales also make it possible to follow changes in weight without directly handling the hive. In all cases, compare the result with previous checks and with comparable colonies in the same apiary.

If the stores appear normal, add nothing. Where a risk of starvation is clearly established, place fondant as close as possible to the cluster, generally directly above the frame top bars. This measure belongs to emergency feeding and is not a practice to be applied to all colonies.

Points to watch
The design of some hives does not always allow a block of fondant to be placed easily directly above the winter cluster. It is therefore useful to prepare the necessary equipment in advance so that an emergency can be dealt with quickly, without having to improvise or keep the hive open for a long time at low temperatures.

Liquid feeding is not suited to the winter phase. It requires the bees to process and store a solution rich in water, can increase humidity and risks unnecessarily stimulating colony activity.

Fondant does not correct the consequences of a colony that went into winter too weak, too heavily infested or with poorly arranged stores. Its use must meet a concrete need and remain accessible to the cluster.

Further reading

• Principles of feeding bees
• Making your own fondant

6. In the workshop / organisation

Objective To use the quiet period to prepare equipment and draw the lessons of the past season.

Clean, sort and repair the items that are not at the apiary. Check the brood boxes, supers, roofs, floors, nucleus boxes and frames, then draw up the list of equipment to be replaced or prepared before spring.

Update the hive record cards, the treatments carried out, hive movements and important observations. Rereading the season's notes also makes it possible to identify recurring difficulties: swarming, lack of equipment, late treatments, insufficient stores or irregular monitoring.

December is also a good time to undertake training and to prepare a coherent beekeeping management plan for the following year.

Further reading

• Beekeeping and legislation in Switzerland – What beekeepers really need to know
• Apiary management: beekeeping management plan

7. What is not done now

Objective To avoid late or unnecessary interventions that disturb the cluster without solving the underlying problems.

• Do not open the hives out of mere curiosity: every opening disturbs the colony and should have a clear purpose.
• Do not treat against varroa on the basis of the date alone: the presence of capped brood greatly reduces the efficacy of oxalic acid.
• Do not systematically rearrange the combs, sharply reduce the volume or fit division boards against the cluster late: these decisions should have been taken during winter preparation.
• Do not give syrup or fondant to all colonies: winter feeding is reserved for justified situations.
• Do not handle a visible Asian hornet nest or attempt to destroy it yourself: observe, photograph and report.

8. Depending on the context: creating a future broodless window?

Objective To present a possible line of adaptation if mild winters make natural broodlessness durably less predictable.

In regions where mild autumns and winters regularly maintain capped brood until the end of December, caging the queen in advance could, in the future, make it possible to create a window suited to the winter treatment.

This strategy nevertheless involves a real timing problem. Carried out too early or for too long, caging could reduce the last generations contributing to a sufficiently numerous and physiologically prepared overwintering population. Carried out too late, it does not guarantee that all capped brood will have disappeared at the time planned for treatment.

The appropriate timing would probably depend on the local climate, altitude, the course of the year, colony strength, food stores and laying rhythm. The type of cage and the possibility for the queen to remain in contact with the workers could also play a role.

At this stage, autumn or winter caging of the queen should be regarded as a line of research and adaptation to climate change, not as a standard recommendation of the Bee Health Service. Brood-break methods are already used successfully at other times of the season, but their systematic application in autumn or winter still needs to be evaluated. Comparative trials in different Swiss regions would be needed before an appropriate period, duration and sufficiently safe conditions of use could be defined.

Further reading

• The winter bee
• Practical Guide: 1.6.1 Brood break
• Varroa: the brood break
• Climate warming and beekeeping in Switzerland

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