Alcohol or soap wash
The most reliable field method, but it kills the sampled bees. It is useful when the result matters.
Varroa Mite Count Calculator
Turn a mite wash, sugar roll or CO2 sample into mites per 100 bees, then compare the result with a seasonal treatment threshold.
Your sample
How did you measure the bees?
Sampling method
Colony phase
Treatment thresholds change through the season. Choose the phase that best matches the colony.
Assumptions and notes
- A level half cup is treated as about 300 bees for easy field maths.
- The infestation rate is mites divided by bees, multiplied by 100.
- A low sample does not prove a colony is mite free. Repeat sampling through the season.
- Thresholds used here are practical planning triggers, not a substitute for local inspection advice.
- Always follow the product label for any registered varroa treatment you use.
Treatment thresholds by colony phase
Mite levels are usually shown as mites per 100 adult bees. Treat the threshold as a ceiling, not a goal.
| Colony phase | Typical timing | Treat at |
|---|---|---|
| Dormant | Winter cluster, little brood | 1% |
| Population increase | Spring build-up, before main flow | 1% |
| Peak population | Summer peak, honey supers may be on | 2% |
| Population decrease | Post-harvest, winter bees being raised | 2% |
If a colony is approaching the threshold, do not wait for mites to explode. It is much easier to keep mite pressure low than to rescue a colony once viruses and winter-bee damage are already underway.
How to do a mite wash
- Find a frame with open brood and make sure the queen is not on it.
- Shake bees into a tub, then scoop a level half cup into your sample jar.
- Add alcohol or soapy water and let the sample sit briefly.
- Swirl gently for around a minute, then strain and count the mites.
- Enter the mite count and sample size above, then record the result with the hive notes.
Which sampling method should you use?
Powdered sugar roll
Non-lethal, but less consistent. A borderline result is worth checking with a wash.
CO2 sample
Quick and non-lethal, but recovery varies. Treat the number as a useful indicator rather than a perfect count.
Frequently asked questions
How many mites is too many?
A common working line is around 1% during dormant and spring build-up phases, and around 2% during peak and declining population phases. Local guidance may vary.
How do I calculate mites per 100 bees?
Divide mites counted by the number of bees sampled, then multiply by 100. Six mites in 300 bees is 2%.
Is an alcohol wash better than a sugar roll?
An alcohol or detergent wash is usually more reliable, while sugar rolls are non-lethal but can miss mites. Confirm borderline sugar roll counts with a wash.
Where should I take the sample from?
Sample nurse bees from open brood, after checking the queen is not on the frame. Bees from honey frames can give a falsely low count.
If I am below threshold, am I finished?
No. Mites can build quickly. Sample again through the active season and check again after treatment to confirm it worked.