Varroa Treatments in the US: What Works, What's Resisted, and What's Used Around the World
The widest toolkit anywhere, the resistance that's creeping in, and the reasons hives still crash.
Varroa has been in the US since 1987, and American beekeepers have the broadest set of tools anywhere. That's an advantage, but the same long history means resistance is a real and growing problem, and no product fixes a colony you never monitored. This page covers how to check your mites, what to treat with, what's used elsewhere, and why hives still die despite treatment.
Monitor first (a 60-second how-to)
You can't manage what you don't measure. Shake about 300 bees (half a cup) from a brood frame into an alcohol or soapy-water wash, swirl for a minute, strain and count the mites. Mites divided by bees times 100 is your percentage. Treat at 2 or more mites per 100 bees (1% for high-risk yards near other operations). Do this monthly, tighter in late summer, and again 7 to 14 days after treating. The free mite calculator does the maths and the reminders.
Why hives still crash, even when treated
- Resistance. Amitraz (Apivar) resistance is now documented in parts of New England, New York and the Southeast; the pyrethroid Apistan and the organophosphate coumaphos have widespread resistance almost everywhere. A wash before and after treatment is the only way to know your product still works.
- Reinvasion (“mite bombs”). Robbing bees reload your hives from collapsing colonies nearby. Varroa is an area problem, not a single-hive one.
- Treating too late, or skipping the after-check. Treat on the number, and always confirm it dropped.
What US keepers can use
- Amitraz: Apivar strips, the workhorse where resistance is still low.
- Formic acid: Formic Pro / MAQS, the one common option that reaches mites under the cappings.
- Oxalic acid: dribble or vapor (Api-Bioxal and generics), and now extended-release strips (VarroxSan, EPA-registered in 2024). No documented resistance.
- Thymol: Apiguard and Apilife Var, temperature-sensitive but good for rotation.
- Hop beta acids: HopGuard, a soft option for phoretic mites.
- Older chemistries: Apistan (tau-fluvalinate) and CheckMite+ (coumaphos) still exist but have widespread resistance and residue concerns; most keepers have moved on.
Used elsewhere, uncommon in the US
| Method | Used in | In the US? | What to know |
|---|---|---|---|
| Thermal (hyperthermia) | Europe | No chemical, but rare | Heating the hive to kill mites. Devices are uncommon here and easy to get wrong. |
| Beekeeper-made oxalic/glycerin strips | Common in Canada, NZ | Use the registered version | Prefer EPA-registered VarroxSan over mixing your own, which sits in a legal gray area. |
| Lithium chloride | Research stage | Experimental | Promising in the lab, not registered anywhere. |
The free tactics that work anywhere
- Drone brood removal in spring physically pulls out mites, which prefer drone cells.
- Brood breaks (caging the queen or splitting) open a window where oxalic acid hits nearly every mite.
- Resistant stock: requeen with VSH / hygienic lines (Pol-line and similar).
- Area coordination: the biggest lever against reinvasion. Treat in the same windows as nearby beekeepers.
Track every wash and treatment, with rotation and re-check reminders.
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General information for US beekeepers, current as of 2026. Not veterinary advice; follow product labels, EPA registration and your state's rules.