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Treat when mite levels exceed 2–3% in spring (3 mites per 100 bees alcohol wash) or 3% in fall (before winter bee production). Delay risks virus transmission.
Mite % = (mites counted / ~300 bees sampled) × 100Standard dose: 1 g oxalic acid dihydrate per brood box (deep). Apply with vaporizer when little or no brood present (late fall/winter) for maximum efficacy.
OA dose (g) = number of brood boxes × 1 gFormic Pro: 2 strips per brood box for 14 days (double deep = 4 strips). Apivar: 2 strips per brood box for 42–56 days. Follow product label exactly.
Strips = brood boxes × 2 strips per boxUpdated: July 2026
After broodless period in November: 2 g OA dihydrate total (1 g per box). Treat 3 times at 5-day intervals for 90%+ mite knockdown on phoretic mites.
5/300 = 1.7% — below 3% spring threshold. Monitor monthly; treat if rising before honey flow if using mite-tolerant approach, or treat proactively per your IPM plan.
One brood box: 2 Apivar strips hung between brood frames for 42 days minimum. Do not harvest honey during treatment; remove strips after period per label.
OA vaporization kills phoretic mites only — 80%+ mites are in brood cells during spring/summer. Treat broodless periods or use brood-active treatments (formic, Apivar, thymol).
Apivar requires 42–56 days contact and 2 strips per box. Under-dosing breeds mite resistance and fails to control population. Follow label duration exactly.
Varroa destructor mites require treatment at threshold levels to prevent colony collapse. This calculator determines correct treatment dosage based on colony size, treatment product, and application method per label and research guidelines.