MayaBees · Oregon, US · Pests & Disease · Aug 24, 2026

Post-treatment verification wash: 9 per 300 before, 2 after — does that count as "worked"?

Finished a full Apiguard course on my worst hive (of five) here in the Willamette Valley and did my verification wash yesterday, three weeks after the second tray went on. Numbers: 9 mites per 300 bees before treatment, 2 per 300 after. On paper that's roughly a 78% knockdown, which is about what thymol is supposed to do in decent conditions. But 2 per 300 is still 0.7%, and I keep seeing people say you want to be under 1% going into winter bee production. So — is 2 a pass? Do I re-treat with something else now, or just schedule another wash in a few weeks and watch for reinvasion? Other four hives all washed 0–1 after their treatments.

#varroa#alcohol-wash#apiguard#thymol#treatment-check

▲ 11 votes 💬 4 replies ✅ Solved

4 replies

ImkerinLena · Aug 24, 2026 · ✅ Accepted answer

That is a pass. Under 3 per 300 (1%) after treatment is the standard target, and 2/300 with a 78% reduction is exactly what a successful thymol course looks like. Do not stack another full treatment on now. Instead: wash again in 3–4 weeks, because September reinvasion from collapsing colonies nearby can undo a good treatment in weeks. If that recheck jumps back over 1%, an oxalic option later in the season is your correction, not more thymol.

SkaneBees · Aug 24, 2026

Agree with ImkerinLena. The number I care about most is the recheck, not this one. I have watched a 1/300 hive go to 8/300 in five weeks during robbing season with zero treatment failure involved — the mites walked in on robbers.

GeorgiaWes · Aug 25, 2026

Pass, agreed. One thing though — you said your WORST hive. Worst hives that were heavily infested often have virus-stressed brood already, so watch that colony's brood pattern over the next month, not just its mite count.

MayaBees · Aug 25, 2026

Thanks all — recheck wash going on the calendar for mid-September. ImkerinLena, the oxalic-as-correction framing is helpful, I was about to panic-order Formic Pro. Will report back with the follow-up numbers.

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