Powdered Sugar Test

The varroa board shows the mite drop, the bee sample shows the infestation level. For this, bees are shaken from the top box, from a honey or outer comb without the queen and without brood, onto a sheet and poured into a jar with a 100-milliliter capacity. A full jar holds about 500 bees, or roughly 50 grams. Only with this fixed sample size are the values comparable.

In the powdered sugar method, five heaped tablespoons of powdered sugar, about 35 grams, go in through the mesh of the shaking jar. Shake briefly, leave the bees in the powdered sugar for at least three minutes while gently agitating them once or twice, then shake vigorously over a fine sieve for about a minute. Sieve out the powdered sugar, count the mites against a light background, return the bees to the colony. This requires dry weather, dry bees, and lump-free powdered sugar. In the wash method, by contrast, the bees are frozen and shaken with soapy water; this is similarly accurate but costs the bees their lives.

Recommendations differ on the thresholds. The Swiss Bee Health Service grades by month, based on the 50-gram sample: treatment is required from more than 5 mites in July, from more than 10 in August, and from more than 15 in September. The Bavarian institute in Veitshöchheim rates under 1 percent in early July as unconcerning, 1 to 5 percent as increased infestation pressure, and over 5 percent as an acute danger. A simplified flat rule of 5 mites per sample, i.e. one percent, is also used. The advantage over the varroa board: the bee sample measures a proportion and is therefore independent of colony strength.

All terms at a glance