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Hot Summer in the Apiary: Honey Harvest and Combating Heat

Biology of the Main Nectar Flow in Summer Conditions

The main nectar flow is the period of maximum nectar secretion by plants, during which a strong bee colony focuses on storing reserves, limiting its reproductive instinct. The optimal temperature for bees’ foraging work ranges from 12–35°C; when exceeding 40–45°C, flights are suspended. During this time, bees prefer nectar with a sugar concentration of about 50%, although they collect it starting from a 5% content.

I. Monitoring and Diagnosing the Nectar Flow

The primary control tool is a hive scale.

  • Weight Gains: During a strong nectar flow, the daily weight gain of a hive can range from 1–2 kg to even 8–10 kg for very large colonies, e.g., those combined in spring or before a planned flow.
  • Nectar Evaporation: At night, the weight of the control hive decreases by 1–2 kg (in extremely strong colonies even by 3–4 kg), which is the result of bees intensively evaporating water from the nectar.
  • Harvest Indicators: Signals for honey removal are reduced flight activity, a drop in daily weight gains to 200–300 g, and the mass appearance of ‘robbing bees’ around storage areas for equipment.

II. Protecting the Apiary from Overheating (Hyperthermia)

High temperature inside the hive (above 38°C) inhibits nectar processing and can lead to ‘overheating’ of bees, which at 55–56°C results in the death of the entire colony.

  1. Ventilation Techniques:
  • Entrances: Must be fully opened. Both bottom and top entrances are used to enable free air circulation (so-called vertical ventilation).
  • Separating Hive Bodies: Wooden wedges 10–20 mm thick should be inserted between the bottom board and the brood chamber (on the entrance side) and between individual honey supers.
  • Inner Cover: The corner of the inner cover (e.g., a piece of foil) should be folded back 3–5 mm or 4–5 cm at the rear wall to allow hot air to escape under the hive roof.
  1. Shading and Insulation:
  • Location: Hives are best placed in the shade of trees or shrubs. Of course, hive placement should be planned in early spring.
  • Painting Roofs White: Hive roofs should be painted white or silver to reflect sunlight.
  • Water: Bees cool the brood nest by evaporating water spread on the combs. Constant access to water in a waterer is critical; in hot weather, water should not be exposed to direct sunlight.

III. Honey Harvest

Honey removal must be synchronized with its physicochemical maturity.

  1. Assessing Maturity:
  • Honey is considered ripe when the combs are capped (sealed) by bees over at least 1/3 or 1/2 of their surface.
  • The permissible water content in honey is 18–20%; honey with moisture above 22% is prone to fermentation.
  • Shake Test: If nectar spurts out of the cells when the frame is shaken vigorously, the honey is unripe and not suitable for extraction.
  1. How to Properly Perform a Honey Harvest
  • Preparation: Work is carried out in the morning or evening to minimize the risk of robbing.
  • ‘Clearing’ Frames of Bees:
    • Mechanical Method: Bees are gently brushed off with a soft brush or goose feather into the hive or a transport box.
    • Bee Escapes (Clearing Boards): Inserted under the honey supers 24 hours before harvest, they effectively clear bees from the super.
  1. Transport: Removed frames are placed in sealed, portable boxes to protect them from bee access.
  2. Replenishing: In place of the removed frames, empty frames with drawn comb are immediately inserted to not interrupt the foragers’ work.

IV. Space Management and Swarming Tendency

Heat combined with a lack of space for nectar is the main cause of summer swarming.

  • Volume Principle: The number of hive bodies or supers with drawn comb should be at least twice what is needed for the colony’s current nectar storage requirements.
  • Rotating Hive Bodies: In multi-story hives, rotation is used: the top, full super is moved to the bottom (below the brood nest), and an empty super is placed on top. This stimulates bees to move honey and work intensively.

Proper management of ventilation and timely honey removal not only allow for obtaining the highest quality product but, above all, for maintaining the high biological condition of the bee colony during the most thermally challenging period of the year.

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