Varroa Sticky Boards: How to Do a Mite Drop Count (and What It Can and Cannot Tell You)
A sticky board is the least disruptive way to look for varroa mites. You slide a coated sheet under a screened bottom board, leave it for a few days, and count the mites that fall. You do not open the hive or handle a single bee.
That convenience comes with limits. This guide explains how to run a mite drop count properly, how to read it without fooling yourself, and where it fits alongside the more accurate sampling methods covered in our varroa testing guide and alcohol wash vs sugar roll comparison.
- Sticky boards measure natural mite drop: how many mites fall from the colony over a set number of days.
- Count the mites, divide by the number of days, and track the trend. A rising daily drop is a warning sign.
- Mite drop is affected by colony size, brood amount and season, so it is less reliable than an alcohol wash or sugar roll for deciding whether to treat.
- Use sticky boards for trend-watching and checking treatment effect; use a wash or roll for treatment decisions, and follow product labels and your extension service’s guidance.
What a sticky board measures
Varroa mites constantly fall off bees and out of cells, whether from grooming, dying, or simply losing their grip. On a screened bottom board, those mites drop through the mesh. A sticky board placed underneath catches them so you can count.
The result is a natural mite drop count: the number of mites that fell over a period, usually expressed per day. It is an indirect measure. It does not tell you the percentage of bees carrying mites, which is what most treatment thresholds are based on. That is the main reason it plays a supporting role rather than a lead role.
What you need
- A screened bottom board with a slot for an insert, or a way to slide a board under the mesh. See screened vs solid bottom boards.
- Sticky boards: pre-made gridded sheets, or a plain white board you coat yourself with a thin layer of vegetable shortening or cooking oil spray. A printed grid makes counting much easier.
- A magnifier or reading glasses and good light. Mites are small, reddish-brown and oval.
- A notebook or app to record the date, days on the hive, and count for each colony.
How to run a mite drop count
- Prepare the board. Apply a thin, even sticky coating if it is not pre-coated. Label it with the hive name and date.
- Insert it under the screen. Make sure it sits flat and fully under the colony. Gaps let ants, earwigs and wind remove mites before you count.
- Leave it for a set period. Many beekeepers use around three days. Very short periods are noisy; very long ones let debris bury the mites and give scavengers time to clear the board.
- Remove and count. Count all the mites on the board. On a gridded board, work square by square and tick off as you go.
- Calculate the daily drop. Divide the total by the number of days the board was in. Record it.
- Repeat on a schedule. A single count means little. The same method repeated every few weeks shows a trend.
Tell mites apart from debris. Varroa are oval, shiny, reddish-brown and wider than they are long. Wax flakes, pollen pellets and bits of propolis can confuse new counters. When in doubt, use a magnifier, or ask a club member to look at a board with you.
Reading the results honestly
This is where sticky boards trip people up. The same number of mites on the board can mean very different things depending on the colony.
| Factor | How it skews the count |
|---|---|
| Colony size | A large colony drops more mites than a small one at the same infestation rate. |
| Brood amount | Much of the mite population can be inside capped brood, where it does not fall. Lots of brood can hide mites; emerging brood can release them. |
| Season | Mite populations and brood rearing change through the year, so the same count means different things in spring and late summer. |
| Recent treatment | Many treatments cause a burst of mite drop. That shows the treatment is acting but does not tell you how many mites are left. |
| Scavengers and weather | Ants, earwigs, wind and rain can remove or wash mites away. |
Because of all that, published mite-drop thresholds vary and are generally treated as rough guides. For a decision about whether to treat, most extension services and the Honey Bee Health Coalition’s varroa guidance point beekeepers to an alcohol wash or sugar roll, which estimate mites per hundred bees.
A low count is not an all-clear. If the daily drop looks low but the colony shows deformed wings, spotty brood or a sudden drop in population, do an alcohol wash or sugar roll and talk to an experienced local beekeeper.
Where sticky boards are genuinely useful
Watching for a rise
Repeated counts on the same colony show whether mites are building. A climbing daily drop is a prompt to sample with a wash.
Seeing a treatment act
Mite drop after treatment shows mites are falling. Follow with a post-treatment wash to confirm what is left.
Cold or hard-to-open times
When it is too cold or a colony is too defensive to sample bees, a board gives some information without opening up.
Reading the debris
Wax cappings in rows show where the cluster is in winter. Wax moth droppings or beetle larvae can show other problems.
For more on confirming whether a treatment worked, see our post-treatment mite check.
From count to treatment decision
A mite count is information, not a prescription. If your monitoring suggests mite levels are rising:
- Confirm with an alcohol wash or sugar roll before acting.
- Compare the result to current thresholds from your state extension service or a recognised source such as the Honey Bee Health Coalition.
- Choose a registered treatment appropriate for the season, temperature and whether supers are on.
- Follow the product label exactly. The label is the legal and safety standard for dose, timing, temperature limits and honey super restrictions. Do not use products or methods off-label.
- Re-test after treatment to see whether it worked.
Our varroa treatment guide gives an overview of treatment approaches, and your local association can tell you what works in your area.
Common sticky board mistakes
- Leaving the board in all the time. In many climates beekeepers remove or close the insert outside of counts, depending on ventilation needs. It also fills with debris that hides mites.
- Counting once and relaxing. One low count in early summer says little about late summer, when mite populations often peak.
- Comparing different periods without dividing by days. Always convert to a daily figure.
- Using the board as the only test. Back it up with a wash or roll at key times of year.
Frequently asked questions
How long should I leave a sticky board in the hive?
Many beekeepers use around three days. Too short gives noisy results; too long lets debris bury mites and gives scavengers time to remove them. Always divide the total by the number of days.
Is a sticky board as accurate as an alcohol wash?
No. Natural mite drop is affected by colony size, brood amount and season. It is useful for trends and for seeing a treatment act, but an alcohol wash or sugar roll is the better basis for treatment decisions.
Can I make my own sticky board?
Yes. A stiff white board cut to fit under the screen and coated with a thin layer of vegetable shortening or cooking spray works. Drawing a grid on it makes counting easier.
What does a high mite drop after treatment mean?
It shows the treatment is killing or dislodging mites, but not how many remain. Re-test with an alcohol wash or sugar roll after the treatment period to see whether levels came down.
The bottom line
Sticky boards are a low-effort, no-disturbance way to keep an eye on varroa, especially for spotting a rising trend and seeing a treatment take effect. They are not precise enough on their own to decide whether a colony needs treatment. Use them alongside regular alcohol washes or sugar rolls, follow treatment labels to the letter, and lean on your extension service for local thresholds and timing.
Get local help. Beekeeping is very regional. Your local beekeeping association and your state’s cooperative extension service know your climate, forage and pest pressure far better than any general guide, and many clubs run mentoring programs and equipment loans. Some states and municipalities also require hives to be registered or set rules on where they can sit, so check before you set up or move colonies.