> >I hope Randy kicks in,  but I read a cpl things in that.  First it was a
> late summer/ fall application,  and hot and dry.


Thanks Charlie.  I also wondered about both of those variables.  During our
testing in late summer, the efficacy of single MAQS improved as the amount
of brood was reduced.

This season, at about the same time that Brion applied the single MAQS, we
were experimenting with formic flash boards.  We got far less efficacy than
we did when we experimented with them late last summer.  I do not know
why.  Temps were a bit lower, but the efficacy was far lower, even at a
high rate of formic application.

Our reason for using single MAQS was not to save money, but rather as a
less disruptive treatment when our colonies didn't require a high reduction
in mite levels.  We try to treat proactively rather than reactively, never
allowing the mite level to climb to a level that we need a high efficacy
treatment.  A single MAQS fits that bill nicely.  Why it didn't have the
expected effect for Brion at this time of season I do not know.

I expect that varroa management is going to be a challenge for us in
drought-ravaged California this summer, and especially for those of us who
aren't using amitraz.  I'm surprised that amitraz has retained the degree
of efficacy that it has for this many years, as I expected it to begin
failing much sooner (it's failing or has failed in a number of other
countries already).  After being burned by the rapid loss of efficacy of
fluvalinate and coumaphos, I've been managing varroa by methods that
although more labor intensive, I hope to be more sustainable.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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