This is an excellent article on assessing mite counts in your beehives. Thanks to J.Morgan, Karen Ferguson and SIBA for sharing.
When I lost what I considered my best hive over the winter of 2013, I sent a sample of these bees to the Beltsville bee lab. It came back with a mite count of 10.7 mites per 100 bees. That’s a high count for most people, and certainly for any of my hives. There were no problems with tracheal mites or nosema. Click here to see a video of a deadout similar to the one that these bees were sampled from.
I wanted to better understand how the bee lab ran these tests so I didn’t have to rely on shipping bees to the lab every time I wanted an accurate mite count. It turns out, it’s not too difficult to do accurate mite counts yourself using either an alcohol wash (that kills the bees you will use for your sample) or a powdered sugar method (that doesn’t kill your bees, but coats them in powdered sugar and allows you to dump them back in your hive.) The “best” method is still a philosophical debate. In our club, we have decided that the alcohol wash is a more accurate method, and killing 300 bees (about a half cup) to know the mite loads in the colony is better than watching the entire hive die a slow death as a result of viruses vectored by varroa.