Monitoring of varroa can be done in a multitude of ways. We will cover the common methods below, and also list out common flaws of each method. The subreddit does have a generally preferred method, which we will cover in the summary of this section.
The sugar roll is quite similar to an alcohol wash. Take 300 bees (half a Cup), and put them in a screened jar. Add roughly quarter cup of powdered sugar. Shake vigorously for 5 minutes. The bees must be shaken vigorously for this to be even remotely effective.
CAUTION: High humidity causes powdered sugar to clump, making coverage much more difficult to achieve, if not impossible. If you must test in particularly humid or sticky weather, consider another method.
If the bees expel their nectar and moisten the powdered sugar to the point that it’s turns into a syrup and is longer powder, add another quarter cup of powdered sugar. Again shake violently for another few minutes. The bees must be coated head to toe in powdered sugar and be completely dry, and must be shaken for a very very long time to ensure the mites are sufficiently dislodged.
Once finished remove the lid and shake, vigorously again, the powder from the bees into fresh water. The bees, once free of powder, can be released into the hive where they will slowly die from having their braincells rearranged by the walls of the jar.
Count any mites in the water carefully.
The mite count is (mite count) / 3 for a percentage figure of phoretic mites in the hive.
The alcohol wash is exactly the same as above, except use a half cup of alcohol solution instead. The stronger the alcohol, the more effective the wash will be. If using commercial isopropyl rubbing alcohol, make sure it is at least 70% strength.
Instead of alcchol, you can use soapy water, but we recommend adding some dishwasher rinse-aid to the soap solution so that any bubbles clear from the solution more readily after shaking. Proportion is 10 mL of dish soap per liter of water, or a quarter teaspoon of soap per cup of water.
Count the mites in the liquid. (mite count) / 3 for a percentage figure of phoretic mites in the hive.
Similar to above, take 300 bees (half a Cup) and add them to a screened jar. This needs to be a varroa counting jar, as you need an isolated environment to gas the bees. Examples of this are the “Varroa EasyCheck” by vetopharama.
Inspection boards are the boards that slide in under an open mesh floor (OMF). Counting varroa this way is incredibly inaccurate, and all it shows you is how many mites died and fell from the bees. It does not give you an indication of varroa count inside the hive in any way.
Mites prefer to reside on the under side of bees. You can visually see mites on the backs of bees, however at the stage where you can see mites on the backs of bees regularly the mite problem has likely already gone quite far.
Varroa are exceptionally small, and without lifting workers from the frame to inspect their bellies, a mite count by visually checking bees is incredibly inaccurate and useless in terms of understanding mite load inside a hive.
A harbo assay is used to measure mite pressure by assessing the mite presence inside a sample of drone brood. This method is mostly used to determine if the colony has varroa sensitive hygienic behaviors (VSH). This method is largely used by VSH breeders, as measuring varroa inside almost fully-cooked brood is the only way to accurately determine if the colony is expressing VSH genetic behaviors without performing expensive genetic testing. This is not something that should be done by a hobbyist looking to measure their varroa load.
There are 2 gold standards when it comes to measuring mite loads: the alcohol wash, and the soap water wash. Both of these have the downside of killing bees, however to accurately determine varroa loads, the varroa also need to die and fall from the bees.
Sugar shake is a somewhat popular method used by hobbyists, but is not used outside of hobbyist circles due to it’s unreliable accuracy.
If you are going to sample bees for varroa, our suggestion is this: Do it properly. There is no point taking inaccurate samples of bees and using that as a gauge for treatments - You might as well not be taking the count at all. We as a community have seen countless posts on the subreddit of people having colony collapses after taking mite counts with sugar rolls, never getting high readings and then collapsing of Parasitic Mite Syndrome (PMS).