Measurement is the foundation of Varroa control. This page covers the simple tools used for counting.

Floor tray

A surface placed under an open mesh floor to collect fallen mites.

• A sticky coating stops mites blowing away or being carried off by ants
• A grid keeps the bees from reaching the tray
• It is left for a set number of days, the mites counted and divided by the days

Easy but the least reliable method: the rate of drop varies with colony size, amount of brood and season. Good for a trend, weak for a decision.

Wash jar

A double vessel for sugar or alcohol washes. An inner screen holds the bees while the mites pass through.

• Alcohol wash: The most accurate; the sampled bees are killed
• Sugar roll: The bees survive; it catches slightly fewer mites and performs poorly in humid weather

The sample is about 300 bees — roughly half a cup. Using a measured container makes the result repeatable.

Uncapping fork

Used to open sealed drone brood. Because the mite prefers drone brood this gives early warning.

The same tool is used for Tropilaelaps screening; for that mite uncapping brood is the principal method.

Sampling rules

• Take the sample from the brood chamber, not the super; mites concentrate on nurse bees
• Do not take it from the frame carrying the queen
• Measure each colony separately
• Keep using the same method so the numbers stay comparable

Records

Write down the date, the method and the result. If you treat, record the count before and after.

Resistance is only noticed by comparing those two numbers. A beekeeper who does not measure may repeat an ineffective treatment for years.

The most critical measurement

The most important measurement of the year is in late summer. Winter bees are reared then; the mite level in August largely determines how many colonies are alive in March.