If people mellow with age what was the Old Drone like when he was young and
vitriolic?
 
 Formic acid can be a very nasty substance but it works well enough.  We have
had Varroa since 1992 yet beekeepers only a dozen miles from me have used
nothing but formic acid to control it and they are still keeping their bees.
One of the advantages of formic acid is that it kills mites within capped
cells.
 
My friends mentioned above have applied the acid by soaking an absorbant pad
with a measured dose which is placed in a perforated plastic bag and put into
the hive in a position where the fumes can circulate around the brood nest
where the greatest concentration of varroa will be found.
 
The latest method of applying the acid is to suspend a small closed tank of it
in the hive from which it evaporates via a pasteboard wick.  I tried this last
Autumn.  I was not scientific enough to count the mite drop but all the hives
survived the Winter.  When I went to take one evaporator tank out I found that
not only had the bees chewed the wick somewhat but they has built some brace
comb on it as well. They can't mind it too much.
 
I have never heard of anyone spraying formic acid and wouldn't recommend it.
I once got a very slight whiff when refilling a tank and I definitely don't
want to again.  A weak solution of lactic acid has been sprayed.  I don't know
the result.
 
Commercial organisations haven't been interested in promoting the use of
formic acid because it is so cheap: there's no profit in it for them.  If they
can turn it into a fancy gel and sell it for ten times the price I can only
applaud their enterprise.
 
If a person is competent to fill the tank of his car with petrol  (I nearly
wrote "fill his car with petrol" which is not what I meant) or to boil a
kettle of water to make a pot of tea or to spray the greenfly in his garden or
to apply cleaner to her cooker or to drive the said car that person is
probably competent to apply formic acid to bee hives.
 
Chris Slade