It seems that every beekeeping group has its own way to monitor Varroa mites. I keep hearing variations on the sugar shake (or sugar roll), the alcohol wash, and the soap bath. But one thing remains constant: most hobby beekeepers don’t want to kill bees in order to count mites.
The powdered sugar shake does not kill bees. The sugar-coated honey bees are easily added back to the hive and the sugar consumed. Both the alcohol wash and the soap bath give a slightly more accurate count, but both kill the bees. Soap and alcohol give more accurate results for two reasons: they better separate the mites from the bees and they allow an actual count of the bees in the sample instead of an estimate.
However, it is my opinion that beekeepers are more likely to monitor if they don’t have to kill bees in the process. I also believe that the easier it is to do, the more likely it is to happen. Furthermore, I don’t think the last scintilla of accuracy makes much difference. Your decision to treat or not treat will probably be unaffected by the one or two mites you missed.
If you are uncomfortable with the difference, you can try this at home: Do a sugar shake and count the mites. Next, use alcohol on the same group of bees and count the extra mites. In most cases, you will find that the sugar shake dislodged at least 90% of the mites.
If you want, you can assume you are getting 90% of the mites with your sugar shake, and then you can adjust the estimate by dividing your count by 90%. For example, if your sugar roll yielded 8 mites, then 0.9χ = 8, so χ = 8.8 mites. Let’s call it 9. But do I think this is a necessary step? No.
In the interest of simplicity I have distilled a number of sources that describe how to do a sugar shake and tried to make it as easy as possible.
Simple Instructions for a Sugar Shake Test (Sugar Roll)
- A mason jar with a marking at the 1/2-cup level. Some mason jars come with embossed measurements, or you can draw a line with a marker.
- A mason jar ring fitted with a round disk of #8 hardware cloth. This lid must fit on your mason jar.
- Confectioner’s sugar (powdered sugar or icing sugar)
- A spoon
- A container for counting mites. It should be white or at least very light colored so the mites can be seen.
- A bucket, bowl, feeder, Tupperware container, or something that you will shake your bees into.
- A small amount of water
Prepare all this equipment in advance. If you use a 5-gallon bucket to catch the bees, you can put the rest of your equipment in there for transport. Once in the apiary, lay out your equipment.
Now, here are the steps:
- Remove 1 or 2 frames of bees from the brood nest. Ideally, these frames will contain open brood and nurse bees. Make sure the frames you shake do not include the queen.
- Shake the frames over your bucket. Don’t bang the frames, just shake.
- Take your bucket of bees, tap it so the bees collect on the bottom, and then pour them into your mason jar up to the 1/2-cup line. This will give you approximately 400* bees.
- Quickly screw on the modified lid.
- Pour the rest of the bees back in the hive.
- Spoon some confectioners sugar onto the mesh screen and work it through with your fingers.
- Shake the bees in the jar for about a minute to completely coat both bees and mites, using as much sugar as necessary.
- Invert the jar and shake it into your light-colored dish. Keep shaking until mites and sugar stop falling out.
- Add a small amount of water to your dish of mites. This dissolves the sugar and makes the mites easier to see.
- Count the mites.
This concludes the actual test. Next you will need to consult a chart in order to decide if you should treat for mites. Recommendations vary depending on the season and where you live. Also, recommendations may be given based on the number of mites per bee, in which case you will have to divide your mite count by the estimated number of bees in your sample.
None of the methods mentioned above—sugar, soap, or alcohol—count the mites under the brood caps, but most of the charts available take this into consideration. If you are uncertain, but sure to read the fine print.
Although this system is not perfect, it will give you a lot of information for a very small amount of effort. Give it a try and see how your mites are doing. One way or the other, you might be surprised.
*Estimates vary. According to Marla Spivak at the University of Minnesota, there are approximately 100 bees per fluid ounce.