Practical Guide: 4.7.5. Managing the Swarming Impulse

Practical Guide 4.7.5 presents spring swarming as a natural behaviour essential to the survival of the bee population. It also notes that swarms that depart have little chance of surviving long-term in the wild in Switzerland, that they can transmit diseases, and that they can cause conflicts or dangerous situations in urban areas. For beekeeping, the departure of a swarm generally means a loss of honey yield and requires particular attention to the colony that has swarmed.

Official Practical Guide (BGD / SSA) – Summary

Practical Guide: 4.7.5. Managing the Swarming Impulse (V 2603)

• Swarming season: The swarming impulse can set in as early as the beginning of wild cherry blossom and persist through the lime tree flow. Field observations also indicate that pollen-rich summer flows, such as the chestnut flow, can trigger a renewed swarming impulse.
• Factors that limit the swarming impulse: dynamic brood nest management, building of drone frames, comb-building activity in the super, expansion of the brood nest from wild cherry blossom onwards using recently drawn combs or foundation placed at the edge, regular removal of bees or brood frames, timely addition of the super, young high-quality queens selected for low swarming tendency, and shading of the front of the hive during midday. Field observations also suggest that regular forage conditions or an early forest honeydew flow inhibit the swarming impulse.
• Factors that promote it: changeable weather, prolonged periods of poor weather, a large bee population, or abundant food with capped honey frames above the brood nest — resulting in insufficient space in the hive and a lack of empty cells for laying.
• Early signs: Empty queen cups or a few queen cells containing an egg are early signs of a swarming process, though they do not necessarily lead to the departure of a swarm. A large number of cells containing an egg, however, indicates that the swarming impulse has taken hold. Queen cells with developing queens are an unmistakable sign that a colony is preparing to swarm.
• Further warning signs: slow comb-building, several starter strips side by side in the drone frame, reduced foraging activity, a large mass of bees with a high proportion of capped brood and little laying space, many inactive bees visible behind the window of a Swiss hive, large areas of stored pollen, and few or no eggs and young larvae despite the presence of the queen and available laying space.
• Types of queen cells: Swarming cells appear when the colony is about to divide; they are typically numerous at the edges of brood frames or on the drone frame, and once capped, swarm departure is possible. Supersedure cells serve the natural replacement of an ageing or failing queen and should be left in place unless the beekeeper replaces the queen. Emergency queen cells appear after a sudden queen loss; removing all but one cell — or at most two in cases of uncertainty — prevents swarming.
• Swarm prevention with nucleus formation: The practical guide describes the artificial swarm with queen, the nucleus colony with queen, and the flying split. When swarming cells are present, all swarming cells must be removed. Nine days after nucleus formation, all emergency queen cells must be destroyed except one — or at most two in cases of uncertainty. Leaving more than one cell already carries a certain risk of swarming.
• Swarm prevention without nucleus formation: Queen cells are removed every 7 to 9 days. If they are already capped, swarm departure remains possible after their removal. To locate all cells, it is advisable to shake the bees off the frames. If the swarming impulse does not subside after two or three removal rounds despite sufficient laying space, or if the bees are very agitated, have stopped foraging, the queen has stopped laying, or only a small brood nest remains, an alternative immediate measure must be chosen.
• Alternative immediate measure: Remove the queen and all swarming cells. Nine days after the colony has been made queenless, remove all emergency queen cells except one and allow the queen to emerge, or remove all cells and replace them with a cell containing a queen about to emerge.

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