One of the uncomfortable lessons varroa teaches us is that a hive can look perfectly good from the outside and still be heading for trouble.
You can have bees flying, pollen coming in, brood in the box and a colony that looks, at a glance, like it is doing what bees should be doing.
And it may be. But it may also be carrying more mites than you think.
That is the hard part with varroa. It does not always give us an obvious warning sign early enough to be useful.
By the time a colony looks weak, the problem may already be well advanced.
A number worth keeping in your head is this: even without extra mites arriving from outside, varroa numbers inside a hive can roughly double every 30 days.
But that does not mean one mite simply becomes two, then four, then eight in some neat little line. In a real colony, mites are reproducing inside capped brood cells while other mites are riding around on adult bees. Some are visible in an alcohol wash, but many are hidden under cappings where we cannot count them.
When that brood emerges, more mites emerge with it. Some of those mites then move into fresh brood cells and start the cycle again. If there is drone brood in the hive, the build-up can be even stronger because drone cells stay capped longer and give mites more time to reproduce.
So the alcohol wash is not showing the whole mite population. It is showing the mites on the adult bees in your sample at that moment.
Then, if mites are also arriving from collapsing colonies nearby through reinfestation, the numbers can climb much faster than expected.
That is why a hive can move from “looks alright” to “in serious trouble” in a very short time.
This is where reinfestation becomes such a problem.
As wild, unmanaged or neglected colonies collapse, mites do not simply disappear with them. They can be carried into surrounding managed hives by drifting bees, robbing bees, drones and general bee movement across the landscape.
So a hive that had a low mite count after treatment may not stay low if it is sitting in an area where other colonies are falling over.
That also helps explain why one apiary can be fairly stable while another, only a short distance away, suddenly gets hammered.
Same beekeeper. Similar treatment. Different result.
The bees are not working from the same spreadsheet.
Local pressure matters.
This is why alcohol washes are still one of the most useful tools we have. They give us a number instead of a feeling. And feelings are not enough anymore.
A half-cup alcohol wash samples roughly 300 bees. If you find 9 to 15 mites in that wash, the colony is sitting around the 3–5% infestation range. At that point, serious damage may already be happening and the colony may be at risk of collapse, failure or absconding.
But lower numbers matter too. Two or three mites is not the same as zero, especially if you are in an area where other colonies are collapsing nearby.
The trend is often just as important as the single result.
One wash gives you a snapshot. Several washes over time tell you the story.
If a hive goes from 1 mite to 3 mites to 8 mites, that is a very different situation from a hive that sits at zero or one across the same period.
This is where records become your friend.
Nothing fancy is required. A notebook, spreadsheet, hive card or phone note will do. The important thing is to write down the date, the hive, the mite count and what treatment, if any, has been used.
Otherwise it is very easy to fool ourselves.
We remember the hive as “looking good.” We remember that we treated it. We remember that the bees seemed settled afterwards.
But without a mite count, we do not actually know what happened.
Treatments are tools, not guarantees.
A treatment may reduce mite numbers, but it may not remove them completely. It may also perform differently depending on brood levels, weather, colony strength, product placement, resistance, and reinfestation pressure from outside the apiary.
That does not mean treatments are useless.
Far from it.
It just means we need to check.
The practical message is pretty simple:
- Wash regularly.
- Write the result down.
- Watch the trend.
- Act before the colony looks sick.
That last point matters.
If we wait until a colony looks obviously wrong, we may already be late.
In the Northern Rivers, we are learning that varroa pressure can be patchy, fast-moving and very local. Some apiaries may build slowly. Others may rise quickly because nearby colonies are collapsing. Some hives may cope better than expected, while others can decline in a hurry.
The only way to know what is happening in your own boxes is to measure.
- A strong-looking hive can still be carrying a dangerous mite load.
- A quiet hive may be hiding a problem.
- And a hive that looked safe last month may not be safe today.
Regular alcohol washes and simple records are not just admin. They are how we replace guesswork with timing.
And with varroa, timing may be the difference between saving a colony and arriving too late.