Treating varroa
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Treat to a count, not to a calendar
Everything downstream depends on having counted. Treating a colony that does not need it selects for resistance, and not treating one that does kills it in February. The count is what makes the decision, and current published thresholds sit lower than older guidance did.
The families
- Organic acids. Formic and oxalic. Formic penetrates capped brood, which is unusual and valuable. Oxalic does not, so it works best when there is little or no brood.
- Essential oil based. Thymol products. Effective and strongly temperature dependent.
- Synthetic miticides. Amitraz and pyrethroid strips. Effective and the family where resistance has developed most.
- Mechanical. Drone brood removal, brood breaks, screened bottoms. Slow on their own, useful as part of a program.
Timing that actually matters
The late summer treatment is the consequential one. Penn State's framing is that low mite levels in late summer and early fall are what allow winter bees to survive, because those bees are being raised right then and mites damage them as they develop.
A colony treated in October has already raised its winter bees under mite pressure. The timing is not about killing mites, it is about which bees get made.
What integrated management actually means
Not "use several products". It means monitor, act on the count, rotate families so resistance does not build against one, and use mechanical methods to reduce the load the chemistry has to carry.
Rotation is the part people skip, and it is covered in treatment resistance and rotation.