Practical Guide: 1.5.3 Wash Method

The wash method (also referred to as the “wash tower”/“washing procedure”) is used to wet bees with a liquid in order to dislodge and quantify Varroa mites from brood chambers and from the bodies of the bees. It is used for diagnostic purposes and does not replace treatment. The following summary is based on the official Practical Guide 1.5.3 of the Swiss Bee Health Service.

Official Practical Guide (BGD / SSA) – Summary

Practical Guide: 1.5.3 Wash Method

• Purpose: Quantitative assessment of the Varroa mite infestation level in bees by controlled washing of bees in a liquid.
• Required material: Collection container (e.g. bucket with lid), fine-mesh sieve or Varroa tray, funnel, measuring tools, washing liquid (e.g. lukewarm water with detergent or special washing gel), bees to be sampled.
• Basic principle: A defined number of bees (e.g. 300–400 workers) is placed in a container with liquid, briefly washed, and the dislodged mites are collected and counted. The number of mites in relation to the number of bees determines the infestation level.
• Steps:
  • Collect 300–400 bees from the brood nest and place them in the collection container.
  • Add liquid (e.g. lukewarm water + detergent) and shake/“wash” the container.
  • Collect the mites using a sieve/base and count them.
  • Convert the result into mites per 100 bees (to assess the infestation level).
• Evaluation: Depending on the infestation level and timing, the wash method can help assess the need for Varroa treatments or monitor the effectiveness of measures taken.
• Note: The wash method is a diagnostic and monitoring method and not a primary treatment or control method.

► PDF of the official Practical Guide (DE)

► Official Practical Guide overview (bienen.ch)
Note: Section Varroa management → 1.5.3 “Wash Method”.

Summary based on Practical Guide 1.5.3. Last review: 01/2026.

Learn more:

• Practical Guide 1.5.1 Natural mite fall
• Practical Guide 1.5.2 Powdered sugar method
• Practical Guide 1.1 Varroa concept
• Recommended Varroa treatment concept and survival rate