Dr. Marion Ellis' (Univ. of Nebraska)BeeTidings Jan. 2000 has complete
details on this method of detection.
Go to:
http://ianrwww.unl.edu/ianr/entomol/beekpg/tidings/btid2000/btdjan00.htm#Art
icle2

Using Powdered Sugar to Detect Varroa

While seeking ways to recover varroa mites from bees for laboratory assays,
Paula Macedo, a University of Nebraska Graduate Student, found a new way to
check colonies for varroa that is more efficient than ether roll. In
addition to being more efficient, it is not necessary to kill bees to
conduct the test.

You will need the following:

A wide mouth canning jar (quart or pint) with two-piece lid.
#8 mesh hardware cloth (or any other mesh that will retain the bees while
letting varroa pass through).
Window screen (or any other fine mesh hardware cloth that will let powdered
sugar pass through but retain varroa.



Retain the metal ring that comes with the two-piece lid, and discard the
center portion. Cut a circle of #8 mesh hardware cloth to fit inside the
ring. Collect 200-300 bees in a wide mouth pint or quart canning jar. Add
powdered sugar to the jar through the #8 mesh lid (enough to coat the bees,
1 tsp. to 1 tbsp. should be adequate). Roll jar around to distribute the
sugar. Allow the jar to sit for a few minutes while you collect additional
samples. Then invert the jar and shake to recover the mites. The bees will
remain in the jar, and the mites and sugar will pass through to a piece of
paper. The sugar will make it difficult to count the mites. You can pour the
sugar and mites into another jar with a fine mesh lid. Shake again and allow
the sugar to escape. Then, dump the mites on a clean sheet of paper and
count them. A brief shaking will usually recover 70% of the mites. If you
persist a little longer you can recover 90%.

We can think of three possible reasons for the efficacy of this technique:

Varroa mite legs have a sticky pad called the empodium that helps them
adhere to their host. The presence of powdered sugar could make it difficult
for mites to adhere to their host.
Powdered sugar stimulates the bees' grooming behavior.
The powdered sugar on the mite's body stimulates mites to release from
feeding to groom themselves. Let us know how it works for you. It may be a
problem in a windy Nebraska bee yard, but it works well in a lab.

Powdered sugar applied to a colony will dislodge a few mites from their host
bees, but it is not highly efficient. Furthermore, the mites will eventually
recover and return to their hosts. However, when bees are isolated from nest
materials, the mite recovery from exposing them to powdered sugar is
impressive. In fact, if you are willing to collect the adult population of a
colony in jars and subject them to powdered sugar shaking, you can lower the
mite infestation comparably to a chemical treatment. Continue shaking until
mites cease to fall, and then return the bees to their colony unharmed. In
future studies, we will examine the efficiency of the technique in bulk bee
cages. One limitation to using this technique is that it is only efficient
when brood is not present. When brood is present, 70 - 80% of the mites will
be in sealed brood cells.

We know that the method is a safe, inexpensive, and highly efficient way to
check adult bees for mites. We hope that you will find creative ways to use
the technique to lower varroa mite infestations and reduce the frequency of
chemical treatments. Dare we even dream of eliminating them altogether.