BethsBees · Ontario, CA · Pests & Disease · Jul 28, 2026

Mite wash jumped from 2 to 8 per 300 right after pulling supers — did harvest cause this?

Second year, three hives in Ontario. Did alcohol washes in mid-June: 1, 2, and 2 per 300 across the three hives. Felt great. Pulled supers on the weekend and re-washed yesterday: 4, 6, and 8 per 300. That's a quadrupling in about six weeks on the worst hive and I haven't changed anything. Nothing else looks wrong — good brood pattern, no DWV that I can see yet. Did pulling the supers somehow concentrate the mites? Did I sample differently? Or is this just what mite growth looks like and my June numbers lulled me into a false sense of security? And at 8 per 300 (2.7%), am I treating now or is that still wait-and-see? I was planning Formic Pro but our forecast is 30°C+ this week.

#varroa#alcohol-wash#treatment-threshold

▲ 16 votes 💬 4 replies ✅ Solved

4 replies

ImkerinLena · Jul 28, 2026 · ✅ Accepted answer

It isn't the harvest, it's the curves crossing: mite numbers keep growing all summer while the bee population peaks and declines after the flow, so mites-per-bee rises even with steady mite growth. Add a shrinking brood nest (fewer cells to hide in, more mites riding adults where the wash finds them) plus late-summer drift from crashing colonies, and June's 2 becoming 8 is textbook. At 2.7% and climbing, treat now — the bees raised in the next few weeks are your winter bees.

SkaneBees · Jul 28, 2026

What ImkerinLena said. On the heat: Formic Pro above 29-30°C gets risky for brood and sometimes queens. Either wait for a cooler window in the forecast, or switch products — with supers already off you have options that don't care about temperature the same way.

TexasBeeSam · Jul 29, 2026

Texas guy here, we live in that heat problem. I've had good results doing Formic Pro's two-strip protocol only when the 3-day forecast tops out below 29, otherwise I go a different route. Also wash all three hives again ~3 weeks after treatment ends to confirm it worked — don't just trust the label.

BethsBees · Jul 29, 2026

Thank you — the crossing-curves explanation finally made it click. Cool front coming through Thursday, so strips go on Friday, all three hives. Will re-wash mid-August and post numbers.

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