Mite Wash Arithmetic

October is when a beekeeper stops being a farmer and becomes an epidemiologist. The winter bees being raised right now are the entire colony until March, and every varroa mite riding a pupa is shortening some winter bee's life. So today was wash day: half a cup of bees from a brood frame of each hive — roughly three hundred bees — into the alcohol jar, swirled, counted. It never stops feeling like a betrayal, and it never stops being the most useful thirty seconds of the autumn.

The counts, with the arithmetic written out so future-me does not have to re-derive it on a cold roof:

hive     bees in wash   mites   infestation
Lark          ~300        4        1.3%
Vesper        ~300        9        3.0%

threshold for autumn treatment: 2%
Lark:   under — monitor, recount in 3 weeks
Vesper: over  — treat now, before winter bees seal

One-point-three per cent for Lark is a pass, barely. Three per cent for Vesper is a fail with consequences: at this time of year mites concentrate in the shrinking brood nest exactly where the winter bees are being made. She gets an oxalic-acid vaporisation series starting this weekend — three rounds, five days apart, to catch mites as brood emerges — and a follow-up wash in November. The vaporiser runs off the truck battery hauled up the stairs, because of course it does.

Why the difference between two hives on the same roof? My best guess is drift and robbing: Vesper spent September robbing out a failing feral colony in the chimney of the fish smokehouse two streets over — I watched her do it, smug about the free honey — and mites ride home on robbers like fleas on a stray. The free lunch was invoiced after all.

Otherwise the autumn is in order. The ivy on the harbour wall is in full flow and both hives smell of it, that hot, strange, cat-adjacent smell that alarms every first-year beekeeper. Ivy honey sets like concrete in the comb, but the bees know how to eat their own groceries. Entrances are reduced, wasp traps rebaited, and the scale says Vesper — of course Vesper — has packed her brood box to the ceiling.