I have been experimenting with a slurry made from FGMO and beeswax.  I
place a large spoonful of the glop on a transparency (the plastic sheets
used with overhead projectors), place another transparancy on top and
smooth the stuff out.  I then proceed to the bee yards where the
transparencies are separated and placed in the enterance of each hive.
I still have mites but a lot fewer than when I started using the
slurry.  It takes about 10 days for the bees to clean off the plastic
transparencies.  A couple of hives have even expelled the offending
plastic sheets when the amount of slurry has been reduced to a point
that they can move it.  I mix 16 ounces of FGMO to about 2/3 cup of
melted bees wax (a little less of 2/3 cup or the slurry becomes too hard
and isn't readily picked up by the bees).
 
Just having fun in Wisconsin!