Recurring treatments, and the doses people forget

Most varroa treatments are not a single event. They are a course: an application, an interval, another application, and often a third. The interval exists because the mites you are trying to reach are protected inside capped brood on the day you treat, and only emerge later. A worker cell stays capped for twelve days, and a mite that went in with the larva comes out with the bee, having raised a family in the meantime.

Which means a half-finished course does something worse than nothing. It knocks back the mites that were exposed, leaves the ones that were not, and gives the survivors a thinner field to breed in. The third dose is the one that gets missed, and missing it is the expensive version of the mistake.

Each family has its own rhythm

The products differ in chemistry, and the chemistry sets the schedule. Labels vary by country and change over time, so the label in your hand wins over anything written here, but the shapes are consistent:

• Oxalic acid reaches mites on adult bees only. When the colony is broodless, in the depth of winter, a single dribble or vaporisation reaches nearly all of them. When there is brood, the vaporisation regimes repeat the dose three or more times, five to seven days apart, so that each cohort of emerging mites meets a treatment. The dribble is usually a single dose, because syrup repeated on open brood does harm.
• Formic acid is the one that penetrates cappings, which is why its courses are short: a pad or strips left in for one to three weeks depending on the product, within a temperature window, and often permitted with honey supers on. The risk it carries is to the queen in hot weather, so the window matters as much as the dose.
• Thymol gels and wafers work by evaporation over two to four weeks, usually as two applications a fortnight apart, and only within a temperature range where they evaporate at the intended rate. Too cold and nothing happens; too hot and the bees may abscond from the brood box.
• Amitraz strips stay in the hive for six to eight weeks and work continuously as bees brush past them, which covers several brood cycles in one application. The dose you can forget here is the removal: strips left in through the winter breed resistance.

A fuller account of the products, their temperature windows and when in the year each fits is in the varroa treatment guide. This article is about the calendar.

Scheduling the whole course at once

When you create a recurring treatment type in BeehiveMind you give it an interval and a number of repetitions, and the app shows you the schedule it will generate before you commit: day 0, day 7, day 14. Applying that type to an apiary creates every dose as its own dated item, each one either pending, done, or explicitly skipped.

The point is not the record. The point is that on the fourteenth day there is something on your to-do list, attached to a specific apiary, that says the third dose is due, and that when you mark it done, the date it actually happened is stored next to the date it was meant to. If the weather kept you away for four days, the record says so, and the next season's comparison of counts is honest about it.

What to write down for each dose

A treatment record that will be useful next year, or to an inspector, has six things on it:

1. The product and the dose, as the label describes it.
2. The date it was actually applied, not the date it was planned.
3. Which hives received it. A course applied to an apiary in the app is recorded against every hive in it.
4. The temperature that week, because most of these products only work inside a range.
5. A mite count before the course, from an alcohol wash or sugar roll of about three hundred bees.
6. A count three to four weeks after it, which is the only evidence that it worked.

The date is also what keeps you the right side of the withdrawal period before the next harvest. In the UK and across the EU, a record of every veterinary medicine given to food-producing animals, bees included, is a legal requirement, and it has to be kept for years. A to-do list that generated the dates for you is a record that already exists.

The count is the verdict

Treatment recorded is not treatment that worked. Resistance to amitraz and to the older pyrethroids is common; a formic pad applied in a cold week does little; a vaporiser that lost its seal did less. The only way to know is a count before and a count after, entered against the same hive, which is why the mite reading sits in the inspection next to everything else. When the trend engine sees a treatment that never moved the count, it says so, and the next course starts from a fact rather than a hope.