Keep the metal ring that comes with the two-piece lid but discard the central portion.

Figure 1. Approximately 7 grams of powdered sugar is added through the hardware cloth.

Cut a circle of the hardware cloth to fit inside the ring. Go into the hive brood area. Find an area with brood, and make sure the queen is not on the frame. Sharply bang the frame into a collection container. Scoop up one-half cup of nurse bees. (Nurse bees are more likely to carry the varroa mites than field bees.)

Figure 2. The jar with bees and owdered sugar is inverted and shaken over a white surface.

Add the powdered sugar through the hardware cloth (Figure 1). Roll the jar to distribute the dust and coat the bees. Let the jar sit for approximately one minute, then invert the jar and shake over a white surface to recover the mites (Figure 2). The bees will remain in the jar, and the mites and dust will pass through the screen (Figure 3). After testing for mites, the bees can be returned to their colony unharmed. Sample colonies in both the spring and fall. When brood is present in the fall, 0.03 or more mites per bee indicates that the beekeeper should remove the honey crop as soon as possible and implement measures to reduce mite populations. This translates to recovering nine or more mites from a sample of 300 bees (one-half cup).

Figure 3. Mites and powdered sugar pass through the hard-ware cloth while bees are retained inside the jar.

In the spring, brood will be present in all normally developing colonies.

When mites are detected with this technique, it is best to implement a strategy to reduce mite populations. If mites exceed the previously described threshold, beekeepers should quickly remove their honey crop and implement measures to reduce mite populations. This may require sacrificing honey production to preserve colonies. Mite populations can increase 10 to 100 fold during the brood rearing season. The rate of increase is affected by the length of the brood rearing season and emigration of mites from other colonies.

Why Do Dust-like Materials Dislodge Varroa Mites from Bees?

There are three possible explanations for the efficiency of dust-like materials in recovering varroa mites from adult honey bees. First, varroa use sticky pads to adhere to their host. Dusting the bees may make it difficult for the mites to adhere or cling to the bees. Second, dusts seem to stimulate the bees' grooming behavior. When dusted, bees begin to groom themselves and persist at grooming for an extended time. A third explanation is that dusts on the mite's body may stimulate it to release from its host to groom itself. The "sugar roll" technique is an inexpensive, efficient and quick way to detect and assess varroa mite infestations. Furthermore, there is no risk of leaving toxic residues in the hive, and the bees can be returned to the hive unharmed after the process.

Citation: Macedo, Paula, Ellis, Marion D. Using the Sugar Roll Technique to Detect Varroa Mites in Honey Bee Colonies, NebGuide, G01-1430-A, June 2001, 2,500 http://ianrpubs.unl.edu/insects/g1430.htm