GeorgiaWes · Georgia, US · Pests & Disease · Sep 2, 2026

The top 5 reasons colonies die over winter — and what to do about each one this month

Every spring this forum fills with dead-out posts, and most were decided in September. So here's my list from 22 years and a lot of scraped bottom boards, in order: 1. Varroa and the viruses they carry — kills more colonies than everything else combined. The fix happens NOW: treat before winter bees are reared, then verify with a wash. 2. Starvation — including isolation starvation, where the cluster starves inches from honey in a cold snap. Heft in fall, feed to target weight, put candy above the cluster as insurance. 3. Queen failure — old or failing queens quit mid-winter. If her pattern is spotty now, requeen or combine now. 4. Moisture — cold condensation dripping on the cluster. Insulation above the cluster, slight upper vent or quilt box. 5. Small clusters — a softball of bees can't heat itself. Combine them (see the excellent uniting thread this week). Notice varroa is #1 by a mile. Argue with me in the replies.

#winter-loss#varroa#starvation#condensation#winter-prep

▲ 12 votes 💬 4 replies

4 replies

ImkerinLena · Sep 2, 2026

No argument on the order — the German bee institutes' monitoring data says the same thing year after year: winter loss correlates with autumn mite load above all else. One addition to your #4: moisture and cold are only lethal together. A dry, well-insulated colony shrugs off -20°C. It's the wet cluster at 0°C that dies. Insulation over the cluster does more than any wrap around it.

muglabalci · Sep 2, 2026

Fifteen years in Muğla and I would only add a #6 for southern climates: winter that is too WARM. My colonies fly all winter, eat stores fast, and rear brood that keeps varroa cycling. The northern beekeepers get a broodless oxalic window as a gift. We do not, so the autumn treatment must be even more thorough.

BethsBees · Sep 2, 2026

Saving this post. Question on #2 — how do you actually learn what a properly heavy hive feels like? Everyone says "heft the back" but my calibration is two winters old. Is there a target weight worth putting numbers on for a single deep plus a medium?

GeorgiaWes · Sep 3, 2026

BethsBees — numbers beat feelings: luggage scale under the back of the hive, lift, double it, roughly. For your Ontario winter you want somewhere around 55-60 kg all-in for that config, and your local club will have the exact target. Do it monthly and write it down; the TREND tells you more than any single weight.

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