Bee Report — Mite Testing

It is now July and Varroa destructor mite populations are likely on the rise, so it is time to start testing the hives regularly. Of all the testing methods, some of which require the beekeeper to kill off drone brood or euthanize a sample of bees, the “powdered sugar roll” (PSR) seems to be the easiest — it is basically delousing with a powder, just like in old-time jails as depicted in movies. Instead of using some sort of insecticide, we can use powdered sugar, which is fairly benign to bees.

Testing for Mites

Mite testing kit: quart jar with screen lid and band, powdered sugar, hive tool, brush, 1/2 C measure, spray water bottle, white tub, cleaning rag, and note-taking material.

To test each hive, I’m following Michigan State University’s PSR method (see also the Bee Informed Partnership instructions). A frame of brood (without the queen) is shaken over a pan and then dumped into a 1/2 C measure. This gets you more nurse bees, which are most likely to hold mites (and reduces variability compared to choosing any old frame of bees). This is then dumped into a pint canning jar and 2 T of powdered sugar is dumped in on top of the bees. A 1/8-in screen cut to cover the lid is placed on top and screwed on with the jar lid (I initially tried it with window-screen material, but this held back much of the sugar when I tried to empty the jar).

First group of tested bees: free of mites!

The lid is covered with the measuring cup and then the whole kit and caboodle is shaken for about a minute. I tapped the jar to make sure the sugar wasn’t sticking to the walls. Then the jar is set in the shade for 2 min to let the mites fall off the bees. The jar is upended over a white tub and shaken to drop the mites and sugar out through the screen before the bees are released back into the hives. They look bedraggled, but the sugar coating will get them some good attention from their sisters in the hive, and I didn’t see any dead ones come out of the jar. I used a spray bottle with water to rinse down the powdered sugar, turning it invisible and revealing any mites, which look like circular brown discs just smaller than the head of a pin. I then used a rag to wipe out the tub between hives.

Luckily, none of my hives had more than one or two mites. Since 1/2 C is about 300 bees, we divide our mite count by three to get our mites-per-hundred bee count. Anything over two per hundred suggests a significant infestation, which would mean you’d need six or more mites coming out in your sugar roll test.


Other than being largely free of mites, the hives are doing really well. In the last update, I discussed how one of the split hives did not have a queen raised. I added a frame of brood weeks ago and they made a queen cell. I added another frame of brood twelve days later to help keep the population up while the queen gestated, emerged, and mated. When I went in yesterday, this hive had eggs laid in a tight pattern in the brood area. Although I didn’t see the queen, the timing is right and the tight cluster of eggs tells me we have a queen (and not a laying worker). Also, the hive was much calmer when I opened it up, as opposed to last time, when they gave a great angry hum when I popped the top, as queenless bees are touchy.

Bees landing on the central door, which has no colony installed.

In the bee shed, I was getting a whole bunch of bees going into my central hive door, although I had no colony installed there. When I opened it up, I had a whole bunch of worker bees just hanging out in an empty box! This is called “drift”: when bees accidentally end up at a neighboring hive. I took them out and shook them loose in front of the shed, after closing the central hive’s door completely to keep them from coming back.

I was able to find one of my new queens and she looks great: good size and active. All of the hives are now queen right with strong brood patterns and good door activity. I don’t know if we’ll get much in the way of honey, but the main goal for us is to go into the winter with four strong hives.


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