1. Priorities of the month

• Give rapidly expanding colonies room in time.
• Look for signs of swarming at every useful inspection.
• Take advantage of strong colonies to form artificial swarms if needed.
• Use the comb-building dynamic to progressively renew old frames.
• Continue the biotechnical measures against varroa as long as they remain easy to integrate.
• Stay attentive to water, food stores and the effects of a return of cold or rain.

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

Objective Clearly locate what makes May a pivotal month at the apiary: colonies develop fast, and decisions taken now largely determine the rest of the season.

In May, colonies often enter a phase of very rapid development. Laying remains sustained, the brood expands, the population increases strongly and the internal balance of the hive can change in a short time.

The central point of the month is simple: accompany this build-up before it turns into congestion, blockage of the brood nest or swarming impulse. This work must always be adjusted to the local context: lowlands, mid-altitude, exposure, weather and blooms do not produce the same calendar everywhere.

In other words, May is not a month of routine but a month of active observation and rapid decisions.

Further reading

• Apiary management: beekeeping management plan
• 10 rules for good beekeeping practice

3. Priority tasks of the month

3.1 Give room in time

Objective Prevent the colony from saturating the brood box at the moment when intake and population are increasing rapidly.

What to look for
The density of bees in the brood box, the actual occupancy of the frames, the state of the brood nest, the space still available for laying, the dynamics of the nectar flow and the comb-building activity. Signs from nature can help: depending on the region, the blooms of cherry, apple, rapeseed or sycamore maple often accompany this phase. Full bloom of dandelion can also signal this shift, without sufficing on its own as a reference.

Concrete actions
Add the super when a colony is truly ready, before the nectar starts to block the brood box. The decision must remain based on the actual strength of the colony and available resources, not on a fixed date. When the comb-building dynamic is favourable, May can also be a good window to progressively introduce new frames and advance the renewal of old frames, without disorganising the brood nest.

Points of vigilance
A super added too late promotes congestion and increases swarming pressure. A super added too early conversely opens a volume that the colony does not yet occupy well, especially in cool or unstable weather. Likewise, comb renewal is conducted in steps: one should not introduce too much new foundation at once into a colony that is not ready to build it.

Further reading

• Practical Guide: 4.12 Dynamic colony management
• The brood volume
• Comb building
• Six good scientific reasons not to use old combs

3.2 Monitor and prevent swarming

Objective Detect the rise of the swarming impulse before it leads to a swarm loss or to a colony that has become hard to manage.

What to look for
Population density, congestion of the brood nest, appearance of queen cells, slowing of laying and, more generally, the behaviour of the strongest colonies. In May, a few days can be enough to change the situation.

Concrete actions
Visit with a clear objective, closely monitor powerful colonies and first address the internal causes of tension: lack of space, blocked laying, excess population relative to the available volume. If necessary, plan a division or an artificial swarm rather than suffering a swarm event. In a phase of strong dynamics, a weekly check on the most at-risk colonies is often the useful minimum.

Points of vigilance
Destroying queen cells without changing the internal conditions of the colony generally remains insufficient. Recovering a swarm that has left is sometimes possible, but it is not the preferred strategy: in May, anticipation is what matters. Postponing an inspection for too long can be enough to let a colony tip over.

Further reading

• Swarm prevention
• Understanding swarming
• Practical Guide: 1.4.7 Increase from swarming impulse

3.3 Make the most of strong colonies through artificial swarms

Objective Turn the strength of colonies into a lever for renewing the apiary, rather than letting this whole dynamic go into natural swarming.

What to look for
The vigour of the colonies, the abundance of brood, the overall quality of the queen and the capacity of the apiary to then follow up on the young colonies created.

Concrete actions
Form artificial swarms when colonies are truly strong. In many apiaries, this allows simultaneously to reduce pressure in the parent colony, to build up reserves for the apiary and to progressively requeen. May often still offers a good window for this work, as long as the young colonies have time to develop well.

Points of vigilance
This is not about splitting on autopilot. One must keep in mind the balance of the apiary, the available equipment, the follow-up on nucleus boxes and the capacity to then correctly manage these new units.

Further reading

• Practical Guide: 1.4.2 Artificial swarm
• Nucleus formation
• Renewing colonies and queens

3.4 Use the comb-building dynamic to renew frames

Objective Use the building season to advance comb renewal without disorganising the colonies.

What to look for
The colony's comb-building dynamic, the actual strength of the population, the availability of resources, and the age and condition of the frames. In May, colonies able to build often offer a good window to progressively introduce new frames.

Concrete actions
In the brood box, May can be used to advance the renewal of old frames. In practice, the classic aim is a gradual rotation according to the three-year rule, renewing roughly a third of the frames each year. This rotation must remain compatible with the strength of the colony and with the organisation of the brood nest.

In the supers, it is also useful to renew frames regularly, even though management is often less tied to as strict a rule as in the brood box. Sorting can be done according to the known age of the frames, their condition, their cleanliness, any deformation and the production context. In regions or situations more exposed to contaminants, vigilance regarding super wax deserves to be strengthened.

Points of vigilance
Renewal is not done abruptly or at random. One should avoid introducing too much new foundation at once into a colony that is not building well enough. For super frames, the absence of pronounced darkening alone is not enough to conclude that a frame can be kept indefinitely: the usage history and the quality of the waxes also count.

Further reading

• Six good scientific reasons not to use old combs
• Practical Guide: 4.4 Comb renewal
• Comb building

4. Bee health

Objective Slow the rise of parasite pressure as long as biotechnical measures remain easy to integrate into spring management.

The best prevention is strong and healthy colonies
It is not necessary to know every disease. What matters is being able to recognise a healthy colony and then to spot what deviates from it. In case of doubt, it is better to seek help quickly and contact the bee inspector.
Useful Practical Guide: 4.7.3. Recognising healthy colonies

Varroa

What to look for
The evolution of the colonies, the presence of drone brood, the regularity of apiary visits and the overall health status. In May, the varroa population also rises with the brood dynamic.

Concrete actions
Continue drone brood removal when this measure is part of the apiary management plan. Monitor the drone frame regularly to act at the right moment and integrate this work into an overall health strategy, keeping the rest of the season in view.

Points of vigilance
Drone brood removal does not replace the treatments and measures to come later. It aims to slow the spring dynamic of the parasite, not to solve the varroa problem on its own. The longer one waits, the more burdensome its implementation becomes in already very developed colonies with supers on.

May disease
In May, one may see in front of the hive young bees that come out, crawl, tremble and cluster on the ground. This picture is classically associated with May disease, often in a context of intense nursing activity, lack of water or unfavourable weather.
Practical Guide: 2.9. May disease

Bee poisoning
In May, acute bee poisonings remain plausible, particularly during the main blooms. Mass-dead, trembling or circling bees should also bring this possibility into consideration.
Practical Guide: 3.1.2. Bee poisoning

American foulbrood and European foulbrood
With brood present, remain equally vigilant against American foulbrood and European foulbrood. A patchy brood, abnormal larvae, sunken or perforated cappings, an unusual smell or a suspicious ropiness test should not be played down.
Practical Guide: 2.1. American foulbrood / 2.2. European foulbrood

Asian hornet
In May, the primary nest of the Asian hornet continues its development and the first workers may appear. At the apiary, moderate vigilance is still sufficient, without slipping into systematic monitoring. Traps are not recommended; in case of doubt, it is better to take a photo and report the observation on frelonasiatique.ch.

Further reading

• Practical Guide: 1.4.1 Drone brood removal
• Integrated varroa control through the seasons
• Development and dynamics of bees and varroa during the year

5. Current food stores and resources

Objective Prevent a very developed colony from finding itself abruptly under pressure after a few days of bad weather.

What to look for
Actual activity at the apiary, access to water, the state of food stores, pollen intake, the general aspect of the brood and possible signs of a local dearth. In May, a big colony can look very strong and then consume very fast if flights are blocked or a local dearth sets in.

Concrete actions
Ensure that a watering point remains accessible nearby. Check food stores when the weather deteriorates. Re-read the signs of the apiary in light of the context: needs are high, but resources can vary widely depending on the region, the current flow and the duration of cold or rainy spells. In a local dearth, do not overestimate the apparent strength of the colony: the challenge remains to prevent rapid tension on water and food stores.

Points of vigilance
May disease is classically associated with a water deficit in a context of intense laying; it is not a contagious disease but a context-related disorder. Chalkbrood can also become more visible when colonies undergo cooling, dampness or spring stress. These situations require precise observation before drawing conclusions.

Further reading

• Water collection and storage
• Practical Guide: 3.2 Dearth periods
• Practical Guide: 2.9 May disease

6. Depending on the context: a first harvest may sometimes be on the horizon

Objective Properly locate the spring harvest: possible in some apiaries but never automatic.

What to look for
The reality of the flows, altitude, exposure, colony strength and above all the actual ripeness of the honey. Depending on the region, rapeseed or black locust may play a role, but neither constitutes a general scenario for the whole country.

Concrete actions
Where a spring harvest becomes plausible, prepare the equipment and base the decision on the actual state of the supers: capping, ripeness and expected quality. Elsewhere, simply continue colony management without forcing the calendar.

Points of vigilance
The date alone is not enough. A harvest that is too early or decided without checking the honey's ripeness exposes you to problems with water content and, depending on the honey type, with crystallisation.

Further reading

• The honey harvest
• Mastering the water content of honey
• Honey crystallisation

7. In the workshop / organisation

Objective Prepare, simply but rigorously, the equipment and the follow-up needed for a month in which colonies evolve very fast.

May requires simple but rigorous organisation: prepare the supers before needing them, keep nucleus boxes ready in case a division becomes opportune, monitor the drone frames without delay, prepare new frames or foundation to be built in advance when comb renewal is planned, and clearly note what has been observed at each inspection.

This month tolerates improvisation poorly: colonies evolve quickly, and a missed visit can cost more than at the start of the season.

Further reading

• Good practice for colony inspections
• Inspections: points of attention
• Practical Guide: 4.4 Comb renewal
• Comb building

8. What we do not do now

Objective Recall the timing or interpretation mistakes that cost dearly in May, when colonies change fast.

• Do not add a super simply because the calendar says so: the real colony decides.
• Do not merely destroy queen cells without correcting the lack of space or congestion: the swarming impulse often starts again.
• Do not neglect water or food stores on the grounds that the colonies seem very strong: a few days of bad weather can be enough to create tension.
• Do not postpone the whole varroa question to the summer: the parasite dynamic is already building up in spring.
• Do not present the spring harvest as a normal stage everywhere: it depends on local flows and the actual ripeness of the honey.

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