>>I OA trickled my over wintering nucs. I killed nearly 
70% doing so. I don't think they had a cleansing flight afterward...

My casual observation is that the hives come through better if they 
are in a loose cluster or can break it for some flying.  It's best to 
treat just before the last bees emerge - the treatment period will 
cover when the last bees emerge.

>>I guess the first site has links to tests done in 
Switzerland, but they are in German. Waldemar, do you read German?

Not fluently but you can request a link to the English-language site 
from Anton Imdorf at the Swiss Bee Research Lab at 
[log in to unmask]  I have a print-out somewhere but would 
have to look for it.  Russians used OA and other acid treatments for 
varroa as long as some 20 or 30 years ago.

Waldemar
Long Island, NY

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