" I am not quite following what your trying to say here about the formic vapors?  Do you think they would in fact disperse at a high level even though on a bottom board???"

What I am saying is a with a formic strip on the bars of a box the vapors are not just going to go straight down due to a density effect.  Bees are moving air thru a hive constantly.  Any turbulence is going to disperse those vapors all over the place and dilute them so fast there is no meaningful density difference.  Plus, there is almost always some natural wind at the hive entrance that is going to blow the vapors all  over the place.  Jaunse said that higher concentrations of formic on the bottom board would kill the varroa that fell off the bees as a result of formic exposure up in the hive.  I just do not think there would be a significantly higher formic concentration on the bottom than you found higher in the hive for strips placed on top of the bars.

I have no opinion on how good formic strips would work if placed on the bottom board.  Might work fine or might not.  A lot could depend on the wind.  If you had wind blowing at the entrance that would help disperse the vapors thru the hive.  I do know if you smoke the entrance with the top off it takes a heck of a lot of smoke to get it out the top as the bees seem to fan it back out the entrance pretty well.  And smoke is warm and thus a bit lighter than air.  I have not used formic so do not know if bees fan a lot to try and clear the vapors from the hive like they do with smoke.
Dick

" Any discovery made by the human mind can be explained in its essentials to the curious learner."  Professor Benjamin Schumacher talking about teaching quantum mechanics to non scientists.   "For every complex problem there is a solution which is simple, neat and wrong."  H. L. Mencken

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