Lots of recent discussion on what works and does not work.  For sure we have a lot of tools to deal with mites.  Perhaps the most important tool we have is Randy's mite calculator.  I encourage everyone to spend a few hours playing what if with that calculator.  It really opened my eyes.

A big problem in getting advice from others on how to deal with mites is there is no one formula that works for everyone.  How the mite population varies depends greatly on your particular location.  Things like temperatures and nectar flows and pollen availability all have major impacts on mite populations as those things govern how much brood a hive has.  The guy that goes to Almonds in Feb and ends the year in Texas on a October flow has an entirely different mite problem than I have here in NE Ohio where my bees right now likely have hardly any brood at all and in some cases zero brood and will have ended brood rearing sometime in Oct.  Someone at my latitude but who has a major pollen dearth for much of July and August has an entirely different mite issue than I have.  If the three of us swap advice it is bad advice due to different conditions.  It is hard to appreciate how important such factors are until you have spent hours with Randy's mite model and looked at what different amounts of brood at different times means in terms of mite population growth.

I used to think a wash of 2% August 1 where I live was a great number.  Now I think a 2% wash August 1 is ok for a young nuc with only a frame or two of brood and four or five frames of bees, but a disaster for a production hive that makes over 100 pounds of total honey over the season.  The later is a dead hive, probably by Christmas, while the former will most likely be fine next spring.

One thing that really comes home from that calculator is if a hive starts to get away from you in terms of mites recovery is hard.  In fact, I think if anything the calculator under estimates how hard it is.  The calculator does not account for the high residual virus count after you have killed the mites.  If the mite count is getting away from you it is probable that the virus counts are high. Probable does not mean certain.  That is part of the reason why sometimes such hives make it fine and other times they crash badly IMO.

The other thing I get from the calculator is that there is no treatment threshold where you should automatically treat.  In my climate a 2% wash in April versus a 2% wash in June versus a 2% wash in August mean three different things.  I would be a bit bothered by a 2% wash in April but for sure not feel any panic at all.  I would not be worried at all by a 2% wash in June.  Right now I would panic over a 2% wash in August.  But, that is all geared to my local climate and brood amounts at those times and also assumes production hives, not fairly new, weak nucs.  Move into a somewhat different area with different pollen and/or nectar flows and what wash number is important and when it is important can change a lot.

The short version is I suggest everyone spend several hours playing "what if" with that calculator and perhaps spend less time falling in love with some particular treatment versus other treatment options.  Even if you have a formula you are following for several years with wonderful results it is worth the time spent on the calculator to understand why what you are doing is working.

Dick

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