So the past couple of years I have been using the formic acid fume boards
for varroa control ala West Virginia University.
http://www.wvu.edu/~agexten/varroa/FAFumigat.pdf

Like everything it's a learning experience and I could use some advice.  A
little background info:  I generally run from 6-12 hives because that's
what I have time for plain and simple.  I'm not a fan of persistent
chemicals in my hives and like to be able to do a midsummer knockback
treatment while honey supers are still on (which is what I was up to July
3rd).  I realize there is a formic treatment out there MAQS, but from what
I have read the problems are pretty similar to liquid formic and vastly
higher cost.  I teach chemistry off and on and know how to handle acid and
respect safety.

Last year I got excellent control with few problems.  This Spring
everything went well also.  I closely watch weather before treating.  The
temp topped about 72F Thursday at my place.  I treated them later in the
day (4pmish).  I placed the fume boards above the brood (for some this was
a double deep, others a deep and 2 mediums) below the supers (1-3 supers on
the hives at the time).  I used 100ml of 50% formic, made sure it was
soaked into the pad and did the "shake test" to make sure none would drip
etc.  I was gone for the 4th so just today got out to move the fume boards
(though colonies appeared to be acting normally on the fourth before I
left, most of the bearding gone etc).  In any case it knocked the stuffing
out of the treated hives.  A good amount of dead bees out front but after a
couple of days outside it's hard to tell the age.  The brood definitely
took a good hit too.  I may have one or two queenless.

I guess my questions are as follows:
1) Is there an environmental factor I am missing that affects how rough
formic is on them other than temp (eg humidity or something).

2) Anyone else have experience with liquid formic that knows any tricks/tips

3) Anyone else doing a midsummer knockback, have a level in mind?  I think
the current recommendation for MAQS is to use a single strip or something
no?  Any correlation to amount of formic I should be using?

4) Anything else I should try?

I have a couple of single deep swarm traps I may combine with the ones I
hit too hard apparently.  Will reevaluate in the next few days to see how
they are all doing and make sure they are all queenright etc.

Jeremy
West Michigan

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