Testing For Varroa Mites
Testing For Varroa Mites
Testing for varroa mites can be labor intense and is often not practiced by many new beekeepers. This leads to many colonies perishing during the winter. There are many methods available to test for mites. There is the alcohol roll, the sticky board test and the powdered sugar test. You may find that you prefer one of these over the others. Keep in mind that opinions differ on what is the economical threshold for when you should treat. Again, you'll have to establish your own levels and threshold in what is comfortable for you.
Of these methods that works well is the powdered sugar test. It is fast, easy and gives a fair evaluate. The alcohol method is more accurate, but I find that most beekeepers shy away from killing hundreds of bees to test for mites. The powdered sugar test doesn't kill bees.
Here's how we do it. Get a quart jar used for canning. Cut a piece of screen the same size as the plate lid on the canning jar. In other words most canning jars have the ring and the seal plate. You will use the screen in place of the plate.
I like to gather up 400 bees, which is 1/2 cup. Pour a 1/2 cup of water in your jar, then draw a mark on the outside so you can identify a 1/2 of bees in your jar. Pour the water out and thoroughly dry the jar. Now, place about 2 tablespoons of powdered sugar in the jar. Select a frame from the brood area as this is where mites are more concentrated. Now, gently press your jar against the comb of brood at the top, while holding the frame sideways. Pull the jar downward at a slight angle. The bees will fall right in your jar. Check the level of bees and try and get as close as you can to the mark on your jar. If I have too many I take my hand off the jar and let some fly out. Place the screen lid on the jar. Then shake the bees around so they are coated good with the powdered sugar usually about 3 to 4 minutes. Do not let the powder fall out while rolling the jar around. Now, take a paper plate and start shaking out the mites through the screen from the jar. You'll see mites fall out. Do this until you really aren't seeing any more mites falling out. To help you, watch my video below then read more:
Next, do the math. There are many opinions about how to calculate the results but here is what I do.
I use 400 bees to give me a greater number of bees to test. Now, if I have 10 mites out of 400 bees, it means 10/400= 2.5 percent. But because my powdered sugar shake only revealed the number of phoretic mites, not those beneath the capped cells on pupae, I double it, bringing my percentage to 5 percent.
After doubling my percentage, my threshold is 6% or 3% if I do not double it. If I am over my threshold after practicing my non-chemical approach, then I will consider using formic or oxalic acid.
If this is not clear, why not consider taking my basic beekeeping online course and I'll explain this in more detail. Click here to register now and take this course from the comfort of your home, on your schedule. Start and finish when you want.