Practical Guide: 3.2. Dearth periods

Periods of scarcity are times when bees cannot find sufficient sources of nectar and pollen, which can lead to food shortages for the colony. The summary below is based on official guidance document 3.2 from the Swiss Beekeeping Service (BGD/SSA) and outlines the causes, effects, and practical management measures.

Official Practical Guide (BGD / SSA) – Summary

Practical Guide: 3.2 Dearth Periods

• Definition: A dearth period is an interval during which, due to a lack or low availability of nectar and pollen resources, foraging activity decreases sharply and the colony's supply is reduced accordingly.
• Causes:
  • Unfavourable weather – prolonged rain, cold, or strong winds.
  • Absence of melliferous plants or end of local flowering periods.
  • Transitions between agricultural crops or vegetation phases with no floral attractiveness (e.g. between cherry and linden blossom).
• Effects on the colony:
  • Reduction in flight and foraging activity.
  • Decreased nectar and pollen intake.
  • Potential weakening of the colony, reduced brood care, and loss of vigour.
• Countermeasures:
  • Supplementary feeding: Provide sugar syrup (nectar equivalent) and pollen or substitutes when natural resources are insufficient.
  • Site selection: Move colonies to areas with richer floral resources; take local flowering schedules into account.
  • Resource diversification: Encourage or plant melliferous flowers in the surroundings (trees, hedgerows, wildflower meadows).
  • Monitoring: Regular inspection of stores, flight activity, and brood condition to enable prompt action.
• Practical advice:
  • Adapt supplementary feeding according to weather conditions and colony vigour.
  • Ensure adequate pollen nutrition, which is essential for brood development.
  • Plan for diversity of melliferous resources within the landscape (ideally in local cooperation).

► Official practical guide PDF (FR)

► Additional information on nutrition (abeilles.ch)
Note: section Health & nutrition → 3.2 "Dearth Periods".

Summary compiled on the basis of Practical Guide 3.2. Last verified: 01/2026.

See also

• Practical Guide: 4.2 Feeding
• The quantity of food is decisive

See also:

• Practical Guide: 4.2 Feeding
• The quantity of food is decisive
• Principles of bee feeding
• Pollen consumption and colony development
• Practical Guide: 4.9.1 Transhumance of Bee Colonies
• Practical Guide: 4.9 Choice of Location