Varroa Treatment Timing: Don't Miss the Autumn Window
Why Timing Matters More Than the Treatment Itself
Every autumn, colonies raise the bees that need to survive through to spring — the "winter bees." These bees are physiologically different from summer bees; they live for months instead of weeks. If varroa mite levels are high while winter bees are being reared, the mites don't just weaken adult bees — they damage the developing brood that's supposed to see the colony through winter. Treat too late, and you've already lost the benefit, no matter how effective the treatment is.
Check Before You Treat
Don't treat on a fixed date without checking first. Run a mite count — an alcohol wash or sugar roll on a sample of around 300 bees gives you a real number, not a guess. As a rough guide, more than 3 mites per 100 bees in late summer is generally considered high enough to warrant treatment before winter bee rearing gets underway.
A drop-tray count under an open mesh floor over a few days is a reasonable low-effort alternative if you don't want to disturb the colony for a wash, though it's less precise.
The UK Treatment Window
Most UK beekeepers aim to treat between mid-August and mid-September, after the summer honey has been removed but before winter bee rearing peaks. Treating too early, while you're still expecting a late flow, wastes the treatment on a population of bees that will mostly die off before winter anyway. Treating too late means the winter bees are already compromised by the time the mites are dealt with.
Choosing a Treatment
Options approved for UK use include Apiguard, MAQS, Apivar and oxalic acid-based products, each with different temperature requirements and treatment lengths — check the product instructions against the weather forecast for your treatment window, since several only work reliably within a specific temperature range. Whatever you use, follow the full course. A half-finished treatment can leave surviving mites resistant to that same product next time.
After Treatment
Recheck mite levels two to three weeks after finishing the treatment course. This tells you whether it worked, not just whether you did it. If levels are still high, you have time to reassess and act again before the window closes — but only if you check rather than assume.
Don't Let Other Stress Compound It
A colony recovering from treatment has less capacity to also fight off wasps or robbing bees at the entrance. Keeping entrance pressure low during and after treatment — a Hive-Five Multi-Guard lets you reduce the opening without a separate tool — is one less stressor on a colony that's already working hard to recover.
The Bottom Line
Varroa treatment isn't about hitting a date on the calendar — it's about protecting the specific generation of bees your colony needs to survive winter. Check mite levels, treat within the August–September window, and check again afterwards to confirm it worked.