Two sampling methods provide the best estimates of mite populations. Both involve removing mites from the bodies
of adult bees, then counting the mites to establish a standard percentage measure of mite numbers (i.e., number of mites per 100 adult bees).
The recommended sampling methods in Fiji is with icing (powdered) sugar shake. Practice improves accuracy .
Icing (Powdered) Sugar Shake Method
The Icing (powdered) sugar shake method is non-lethal, so the bees may be returned to the hive after testing, and icing sugar is easily available in Fiji.
- Add approximately two tablespoons of powdered sugar to the jar.
- Vigorously shake the jar for at least one minute to cover the bees in sugar and dislodge the mites from the bees. To improve the consistency of mite counts, shake the jar for a consistent length of time for every sample.
- Set the jar down and wait three to five minutes. (Rushing the process increases the risk of undercounting the mites.)
- Invert the jar and shake it like a salt shaker, capturing the falling mites onto a clean plate or pan below. Shake the inverted jar until mites stop falling out.
- Spray the powdered sugar deposit in the plate or pan with a water mist to dissolve the sugar. Count the mites that remain. Add an additional
tablespoon of sugar to the jar, shake and roll the bees again for 30+ seconds, and repeat steps 4, 5, and 6 to improve the accuracy of the
count. - Count the number of mites in the plate or pan.
- Add an additional tablespoon of sugar to the jar, shake and roll the bees again for 30+ seconds, and repeat steps 4, 5, and 6 to improve the accuracy of the count.
- Count the number of mites in the plate or pan.
- Calculate the mite number per 100 adult bees.
- 10. Sampled bees can be released back into the top of their colony or at colony entrance.
For best results, sift the powdered sugar through a flour sifter to ensure a fine texture.
Do not perform this test in high humidity or during strong nectar flow, because dampness will cause the sugar and mites to adhere to the bees. Do not rush – allow temperature to build up in powdered bees before shakeout.
Counting the Mites
The goal of mite assessment is to determine the number of Varroa mites per 100 adult bees, expressed as the percentage of
infestation.
Counting steps:
- Count the number of mites collected in the plate or pan.
- Divide that number by the number of bees in the sample.
- Multiply by 100 to yield a percentage.
Example: A beekeeper samples 300 adult bees and counts 12 mites in the pan.
12 mites ÷ 300 bees = .04 X 100 = 4% (4 mites per 100 adult bees)
To increase the accuracy of the assessment, count the actual number of bees in each sample. As you gain experience with sampling, your sample sizes will become more consistent.
“Tools for Varroa Management” Guide
The info was based on the Honey Bee Health Coalition’s excellent resource “Tools for Varroa Management” Guide.
