Idaho Honey Bee

Varroa mites are the single biggest threat to honey bees that we have control over. They are in all hives in the United States to some degree. There can low numbers of mites in a hive, and the hive next to it may have a high mite count. They do not kill the bees directly, but they do drag the hive down, making it vulnerable to diseases and viruses that have the opportunity to enter the bee from the mite’s attachment point on the bee. They are about the size of a period in a sentence, and can be seen with the naked eye. They prefer drone brood larva over worker brood larva because of the longer development time in the cell, but will thrive in worker brood just fine. If one tests for them and estimates their numbers in a hive, you can make good management decisions about possible treatment. The count that one should do something at (somewhere between 7-35 depending on who you believe) is up for debate, but the spike in numbers you might catch with regular testing will leave no doubt as to the need to do something. There are several ways to test for mites, but visual observation is not one of them, because you can have a lot of mites in a hive and not see visual indications.
 
The most common technique is to use a screened bottom board with a sliding insert that can be sprayed with cooking oil, and slid underneath for 24 hours, then pulled and checked for mites. Good eyes are needed for this method. The mites, and pollen saturated in oil all look about the same to a new beekeeper, but if you see well or employ a magnifying glass, it is convenient.

A second method involves a pint jar with a screened lid. What you do is choose a brood frame (without the queen) and shake or brush the bees into a plastic tub, or bowl, scoop up ½ cup of them, and pour them into the jar. A heaping tablespoon of powered sugar is added, and bees and sugar are rolled, and shook gently for two minutes in order for the mites to loose their footing, and then the sugar and mites are shaken though the screen into a white tub or onto a paper. You will then easily see the dark red mites against the light color, and there is no oil involved to make you question what you are looking at. The bees can be released with out harm to them.

A third method is like the previous, with a screened jar, but uses 70% rubbing alcohol poured in though the screen several times, and poured out into a white tub. This technique kills 300 bees but is more accurate, and gets a larger percent of the mites off the bees.

The important thing here is to test for mites every 2-3 weeks throughout the season, so you are aware if the mite numbers spike.