Varroa Calculator - Treatment is recommended as soon as practically possible

[charlievictorbravo]

Apiguard is not very effective at all in cool conditions, and will be even less so by reading how some leave the mesh floors open, Apilif-var is much more efficient in cooler weather, or the version of this that i have used since 2002.

From some paper linked on here Apiguard efficiency in cooler weather could kill between 66.9 to 68.3 compared to Apilif 92.4 to 95.1

I have used your Thymol recipe (in the Sticky) for two years and have been pleased with the results. Your comment above, about it being a version of Apilif-var, is interesting. I used the recipe quite late in the season in 2014 and had doubts whether it would be effective. I needn't have worried - in one hive I had a drop of nearly 3000 mites and had to use the full 3 treatments of 2 weeks each to get the average daily drop down to low single figures.

At the end of the treatment, the kitchen roll medium was so chewed up by the bees that I did not attempt to remove it. That does not seem to have caused any problems and may have dropped the odd mite - I stopped monitoring after 6 weeks and left the OMF open, only monitoring again in the run up to Christmas.

Thanks for the recipe, HM

CVB

 

[alanf]

...the Beebase National Bee Unit Varroa Calculator

Hive 1 - 35 (over 14 days)
Hive 2 - 70 (over 14 days)

A follow up now I have some numbers. Back at beginning of December I counted drops to decide whether to treat with oxalic. The numbers predicted by the calculator were high, so I thought why not record the numbers to see how accurate they actually were. Repeated sublimation of oxalic (3 treatments at 6 day intervals) should kill 90-95%+ of the resident mites, or that's the basic assumption.

A bit of reverse engineering first - the NBU calculator for December uses a multiplier of 100 if you choose a "Long" brooding season, 400 if you choose "Medium" or "Short". Unhelpfully it doesn't define the terms but I guess the difference is whether you expect brood or not. Whether you actually have brood is a bit hit and miss unless you look.

Taking my own results, my average multiplier was 160, that is every mite dropped per day in early December resulted in 160 falling during treatment. Individual hives varied from 70 to 260 as a multiplier. Obviously these are my hives, my counts but it's an idea of what sort of range I will be expecting next year.

To take the example counts in the op, 70 in 14 days or 5 per day would put the mites in the 350-1300 range, most likely around 800. 35 in 14 days would be half that. Either way, the NBU advice to treat now is sound, a mite population of 400 in December could be a couple of thousand by April.