>The data  clearly indicate that OAV when brood is present, takes A
LOT of applications to be efficacious. 

This is becoming something close to "settled science"

>I suspect that the humidity hypothesis as far as OA treatments is a red
herring.

This has been my suspicion as well. We too often try to find a geographic or climatic cause and overlook other variables. Replication of an experiment needs to be vigorous.

To sum up my  mite efficacy this past summer. I did 2 trials. 

First I tried  50/50 wt. to wt. OA Glycerin on "Swedish" sponges. N 16, in on June 10, out on Oct 15. 300 bee test pre application all 0-3 mites.  300 bee count post removal, 3 with 1 mite, 1 with 2, and 12 with 0. Clear in my mind, highly efficacious. 

Second I did OAV via Pro-Vap, 3 to 4g on each visit to the yard throughout the season to see if 6 or 7 sporadic treatments would have an effect. They did not. Mite counts were in the same range as untreated colonys post harvest. Past years 6 or 7 treatment at 4 day intervals proved only moderately efficacious and involved more time and travel then I thought worth while.   

OAV and untreated got Apivar late Aug. and for the first time I saw widespread failure. I don't think I can rely on amitraz and will not be using it again.  Had to resort to formic but by then the season was late. Here it goes from too hot to too cold very quickly. The temperature window for formic is narrow between supers off for realistically getting to the brood boxes and nights in the 40s and afternoons still hitting 90. Will do a winter clean-up OAV on a warmish day soon. 

It has been a tough year all around. Extreme heat, lots of melted frames, extreme drought, forage dried up in May, extremely poor honey yield. Not to mention the unmentionables of pandemic and politics. On this darkest day of a very dark year my sincere best wishes and thanks to all on the list. Next year will be better, we deserve one....for a change. 

Paul
47N 119W 2200'

 

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