KentishBee · Kent, UK · Pests & Disease · Sep 18, 2026

Still 6 per 300 after thymol — too late in September to retreat with Apivar before the winter bees are gone?

Third year in Kent, four colonies, and I'm annoyed with myself. Two Apiguard trays, 14 days apart, started on the 8th of August and finished on the 5th of September, ekes on, supers off. Pre-treatment washes were 11, 9, 8 and 6 per 300. Washes yesterday: 6, 4, 5 and 2. Only my smallest colony got under 3. Weather during the first tray was cool, 14-17°C for about ten days, then it warmed up. The strong colonies are on brood-and-a-half. So: is this thymol resistance, did the cool spell wreck the first tray, or am I picking up mites from the untreated hives about 300 m away? And more urgently — what now? Oxalic is out with this much brood, Apivar is six to eight weeks, and I keep reading the winter bees are already being raised. Is there actually any point, or have I missed it?

#varroa#apiguard#apivar#treatment-rotation#alcohol-wash

▲ 12 votes 💬 4 replies

4 replies

BuckfastLinda · Sep 18, 2026

Not resistance — thymol has no established field resistance; it's a temperature-and-application product. Apiguard needs ambient temperatures around 15°C and above to evaporate at the intended rate, so 14-17 for the first ten days means the first tray under-delivered, and on brood-and-a-half the vapour is diluted in a bigger space. And yes there's a point: Apivar now, 1 strip per 5 frames of bees in the brood nest, minimum 42 days, out by 56, supers off — read the label. Then one oxalic treatment in the broodless window. Winter bees in Kent are still being raised into early October.

SkaneBees · Sep 18, 2026

Exactly what BuckfastLinda says. Switching to a different class is the correct move on principle as well — don't hit them with thymol twice in a season. On the neighbour question: reinvasion shows up as a count that CLIMBS in October, when the untreated colonies collapse and your bees rob them out; your numbers now are just a treatment that didn't finish the job. Entrance reducers on, keep inspections short, and re-wash mid-November when the strips come out.

ImkerinLena · Sep 19, 2026

In Bavaria we treat thymol as a warm-weather product and I would not start it after mid-August at all. A count taken one week after the last tray is the fair test, and yours were taken later — but 6 per 300 in mid-September does not need a second measurement, it needs a strip. Treat now and don't lose another week washing to be sure.

KentishBee · Sep 19, 2026

Strips went in this evening: two per colony in the big three (eight to ten frames of bees each), one in the little one, all in the brood nest, reducers on. Removal date written in the diary for the 13th of November and oxalic pencilled in for the broodless window. Thank you all — I was half ready to give up on them.

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