> I seem to recall that there were problems with formic acid prompting
> queen rejection and/or supercedure if used in uncontrolled or high
> concentration, which is why it was not a favorable means of varroa
> control.
 
There are reports of apparent queen rejection.  Especially on
first-ever application.  However, my understanding is that this is a
phenomenon that is not reproducible or well documented or frequent.
There is some suspicion that queens that are infested with acarine
are affected.  Perhaps Kerry will add something to this.
 
Of course any chemical control measure can/will cause problems if
used "uncontrolled or high concentration". Using any chemical
requires education and careful attention to details, as well as keen
observation of the results.
 
One of the major objections to formic acid is its corrosive nature
and the matter of spills and fumes -- particularly when being
transported in a concentrated form.
 
Apparently it is no worse than Muriatic acid which is used routinely
in masonary work, however when anything is is being used in
conjunction with food, additional caution is necessary.
 
Formic acid occurs naturally in many foods, including honey, and is
not toxic (who knows, it might be beneficial) in small doses.  It is
fairly closely related chemically to vinegar.
 
The major reason that it is not permitted in the USA, I believe is
that there is a great deal of cost in getting approval, and there is
no profit for anyone in getting it approved, seeing as there is no
patent, and it is a commodity easily obtained anywhere.
 
In the case of Apistan, I understand there is only a few pennies
worth of the (proprietary) good stuff in the strip.  Most of the
rest is (gross) profit, and the promise of this was sufficient to
provide incentive for the manufacturer to spend the many dollars
necessary to go thru the regulatory approval process.
 
Regards
 
Allen
 
W. Allen Dick, Beekeeper                                         VE6CFK
RR#1, Swalwell, Alberta  Canada T0M 1Y0
Internet:[log in to unmask] & [log in to unmask]
Honey. Bees, & Art <http://www.internode.net/~allend/>