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When to Test & Treat for Varroa Mites

The simple answer is to test monthly during the spring, summer, and fall and treat when your mite count exceeds 2 mites per 100 bees. Anytime the count exceeds that level, you are at risk of the mite count exploding and greatly damaging or killing your hive. However, if you are in the middle of your honey crop, you cannot use many of the mite treatments.

Now for some more depth. There are times of the year when mite populations peak and testing and treating are usually most needed.

Regarding treating outside of the honey flow time frame (unless you use treatments approved for use during a honey flow), treat anytime mite levels exceed 2 mites per 100 bees. Many small-scale beekeepers are able to treat only one time per year if they don’t have hives in areas with dozens or hundreds of hives in a few miles’ radius. For testing, I recommend testing once each month from the time your bees begin bringing in natural pollen in the early spring to the time the first freeze hits in the fall. At the very least, test once in the early to midspring, once in the early summer, and again in the early fall. Always test after you have concluded your mite treatment to ensure it actually worked. Some mite treatments work far better than others!

How to Test for Varroa Mites

The most accurate of the quick methods to test for Varroa mites involves using an alcohol wash. I love the EasyCheck Varroa Mite Check system, which supplies a ready-made wash jar. All you have to provide is the rubbing alcohol and the bees. A similar test can be done using a quart jar; it just does not have a basket to hold the bees like the EasyCheck.

Either way, the methodology is the same:

  1. If you have more than a few hives, see the diagram below.
  2. Pull one frame covered with bees and brood out of your brood box.
  3. Check to make sure the queen is not on the frame.
  4. Vigorously shake the bees off onto an unfolded sheet of newspaper.
  5. Place roughly 300 bees (½ cup) into the jar by quickly picking up both ends of the newspaper and folding and shaking it slightly, creating a slide for the bees to go into the jar. Alternatively, you can brush bees off a frame into an open jar.
  6. Pour about 2 cups of rubbing alcohol or a solution of Dawn dishwashing soap (2 Tbsp. to 1 gallon of water) into the jar with the bees. Gently shake and swirl the bees in the liquid for about a minute.
  7. Hold the jar up and look at the bottom of the jar. You should be able to count individual mites as they settle to the bottom.
  8. The treatment threshold is more than 2 mites per 100 bees. So if you see more than 6 mites you should certainly treat the hive. If you see fewer, test about four weeks later to continue monitoring levels.

The most accurate test is the alcohol method.

CO2 Method Mite Test

Another testing method uses a CO2 injector for a no-kill approach with similar accuracy as the alcohol wash. This method is used with the EasyCheck Varroa Mite Check system.

  1. Follow steps 1-5 above.
  2. Invert the basket of bees you’ve collected into the plastic tub of the EasyCheck.
  3. Loosely lay the yellow lid on top of the inverted basket.
  4. Take your CO2 injector in one hand. With the other hand, slightly lift the yellow lid, allowing only enough room for the CO2 injector nozzle to access the container.
  5. Hold the trigger down on the injector for 5 full seconds. The bees will go to sleep.
  6. Shake the entire container upside down (yellow cap facing down) for 15 seconds, dislodging the Varroa mites from the bees.
  7. Remove the yellow cap and count the mites.
  8. The treatment threshold is more than 2 mites per 100 bees. So if you see more than 6 mites, you should certainly treat the hive. If you see fewer, test about four weeks later to continue monitoring levels.
  9. The bees will quickly regain consciousness and can be returned to the hive unharmed.

Testing using the CO2 method

Sugar Roll Varroa Mite Test

This is also a popular method since, unlike the alcohol wash, it does not kill any bees. However, it has also been shown to be less accurate and does not give a precise mite count. So even though it spares 300 bees, it may cost you your whole hive if relied upon exclusively. However, since it is common, I wanted to address it and give instructions on how to make it as accurate as possible.

  • You will need a pint-size canning jar with a cutout circle of #8 hardware cloth in place of the lid.

The ring can still be used to secure the hardware cloth in place.

  1. Follow steps 1-5 from the previous method.
  2. Pour about 3 tablespoons of powdered sugar into the jar. Shake the bees in the jar for about 30 seconds to ensure they are completely coated with the powdered sugar.
  3. Let the jar sit in the sun for about 2 minutes.
  4. Shake the bees again for about 30 seconds.
  5. Turn the jar upside down and shake all the powdered sugar out through the screen onto a flat surface and count the mites.
  6. The treatment threshold is more than 2 mites per 100 bees. So if you see more than 6 mites, you should certainly treat. If you see fewer than that, test about four weeks later to continue monitoring levels. However, this method does not fully remove all the mites from the bees so the population is most likely higher, possibly significantly so, than whatever you count.
  7. You can open the jar and shake the bees back into the hive or in front of it.

Sticky Board Method for Testing Mites

Not nearly as accurate, but certainly better than not testing at all, using a sticky board can give you a good idea whether you have an overabundance of mites. This method isn't recommended for use on a continual basis, but it certainly works for a quick check.

  1. When using screen bottom boards, install the sticky board on top of the insert that slides under the screen.
  2. Wait 24 hours.
  3. If more than 9 mites in spring or 11 mites in fall or winter have dropped, that warrants treatment.

For solid bottom boards:

  1. Slide a sticky trap with the protective screen cover from the front of the hive on top of the bottom board.
  2. Follow steps 2 and 3 of the previous method.

Testing using a sticky board