Entry 05 · Health
Mite counts, treatment windows and the August I missed
The mites have been in every colony I have ever kept and they will be in every colony I keep next year. Knowing the number, rather than assuming it, is very nearly the whole of my approach.
- At the hive
- 8 June 2026
- Typed up
- 30 August 2026
- Reading
- 8 minutes
- Stand
- the Taunus foothills above Frankfurt
Counting, because guessing does not work
Each hive stands on a floor with a removable tray under a mesh, and from May onwards the tray goes in for three days at a time, once a month. I count what has fallen onto it with a torch and the blunt end of a pencil, divide by three, and write the daily figure on the card. It takes ten minutes. It is also the only number in my notes that has ever changed a decision before the decision had become urgent.
Before I counted, I looked. Looking finds mites when there are a great many of them, which is to say too late. A colony carrying a heavy load in August looks exactly like a colony carrying a light one right up until the day it does not: bees with shrunken wings on the landing board, a brood nest that has stopped expanding, a population falling faster than the queen can replace it. The tray gives me a number in June that predicts that August, and nothing else in my equipment does.
Written on the card
- Tray in for three days, once a month, from May onwards
- Divide the count by three and write the daily figure down
- Compare with the same hive last month, not with a book
- A rising trend matters more than any single number
The August I was three weeks late
In 2023 I treated in the first week of September, because August had been hot and the acid I use is explicit about temperature. That sounded like care and was in fact avoidance. The colony that mattered had been at eight mites a day in the middle of July, a figure I had written down and filed as something to watch. By the time the treatment went on, the bees that were supposed to carry that colony through the winter had already been raised on infested brood.
It came through October looking reasonable and was down to a handful of bees by the end of December. The mites had not killed it in any direct way. They had produced a generation of winter bees that could not do a winter. The lesson I took from it is about dates rather than chemistry: the bees that carry a colony to March are raised in late August and early September, and anything I do after they are sealed into their cells is a treatment for next year's problem.
Two windows, and the weather that decides them
There are two moments on this slope when treating actually helps. The first is the end of July or the very beginning of August, before the winter bees are raised, while the colony still has brood and the air is inside the range the acid needs. The second is the last mild days of December or the first of January, when a colony is broodless and a single dose reaches almost every mite in the box. Everything in between is too warm, too cold or simply too late.
The weather here rarely offers either window cleanly. Formic acid wants days between fifteen and twenty-five degrees, and August on this slope can sit above thirty for a week and then rain for four days. The winter dose needs a broodless colony and an afternoon above four degrees, and some Decembers never go properly broodless at all. I write the intended dates into the notebook in June, before the weather has an opinion, and treat on the first day that qualifies rather than the best one.
Written on the card
- Late July to early August, before the winter bees are raised
- A broodless day in December or January, above four degrees
- Dates written in June, before the weather offers excuses
- Treat on the first day that qualifies, not the ideal one
What the counts look like after four seasons
Four seasons of trays have given me something like a baseline for this stand. A hive under one mite a day in June is fine and I leave it alone. Three or four is the level at which I start watching weekly instead of monthly. Anything above six in July has never ended well in my records, whatever the colony looked like at the entrance, and that is the figure that now gets me up the hill with the acid on the first suitable afternoon.
The counts also settled an argument I had been having with myself about how many colonies to keep. Four is what I can inspect properly in an afternoon, and properly is what the numbers require. The season I ran six, the trays went in late, the figures had gaps in them, and the gaps turned out to be exactly where the trouble was. A small apiary I actually measure is worth more to me than a larger one I visit in a hurry.