Using Mite Monitoring Boards to Count Varroa Mites

Mite Monitoring boards (sticky boards) are an easy way to monitor varroa mite levels in your hive – easy for you and very easy on the bees since you don’t even have to open the hive. Regular, season-long mite monitoring is an essential tool for keeping your bees healthy.

Varroa mites are dangerous pests in nearly all bee colonies. Not only do they harm bees by biting them, but they also spread viral diseases that can kill a strong hive in just a few months. Mite-spread diseases are frequently the cause of winter losses.

There are many mite-control strategies you can use to protect your bees, but first you have to know the scope of the problem. Getting that data requires some form of mite monitoring.

Mite monitoring boards, which measure the number of mites falling from the hive over a period of time, are the least intrusive method. They are a good way to get started on a mite monitoring program. If you do them regularly all season long, you’ll be alerted to any dangerous increase in mite levels in time to deal with it. This will help keep your colony from being seriously harmed by the diseases that mites spread. But you need to do a count every week, not just once in a while, because it’s the weekly trend of mite numbers that tells you what you need to know. Fortunately, using boards is very simple and takes only a few minutes to do.

What you’ll need to get started with Varroa mite monitoring

• A screened bottom board: Many people just stack it on top of their solid bottom board but you can also use one by itself. Using both boards together works very well; they can be left in place year-round. The open slot for the mite monitoring board should face the back of the hive to make tending the board easy.
• A mite collection surface: Either a tray or a piece of white corrugated plastic.
• Any kind of cooking oil: This is a good way to use up oil that has gotten a bit too stale for kitchen use.
• Paper towels
• An inexpensive magnifying glass and wooden toothpicks
• A nice-to-have extra: 3-M Original Blue Painters’ tape; get a roll of 1.88” wide tape and choose the kind with no writing on the tape as that kind sticks best outdoors.

How to do a mite monitoring board count

With the screened bottom board in place, pour 2 tablespoons of the oil on the board and use a towel to spread it evenly. Slide the oiled board into the slot. If you have tape, tape the slot closed to keep bees and ants out.

After three days, pull the board out, close up the slot, and take the board to a well-lighted area to check for mites. Use the magnifying glass to find them, if needed.

Moisten the tip of a toothpick and as you find each mite, use the toothpick to pick it up and set it aside on a clear spot on the board. Once you can’t spot any more, go to the tallying area and count the total you found and divide by 3 (because you tested for 3 days). This number is your average daily mite count. Compare this number with published thresholds for your area and for the season and determine whether it’s time to treat your bees.

Be sure to write down the number of mites you see. If you can, plot it on a graph so you have a visual representation of the mite count as it changes from week to week. When you start counting early in the season, the number should be low. By midsummer the numbers will often start to increase rapidly. Don’t wait until you reach the treatment threshold before deciding which techniques or control methods to use. Be ready to act, since some control methods take longer to effectively reduce the mites in the hive. Continue to use mite monitoring board counts to verify that your control strategy is working, and the mite levels are going back down. And keep on mite monitoring boarding every week.

After making the count, scrape the debris off the board into the trash (not on to the ground to prevent small hive beetle larvae from reaching the soil to pupate). Return the board to the slot until you’re ready to do another test.