Formic Acid is being used extensively in Canada where it is now legal. It has
been used for several years in the U.S. illegally.  Approval has been applied
for by Mann Lake Supply.  Liquid Formic is available from many chemical
companies in the U. S. in 55 gallon drums for about $5.00 per gallon. The
Canadians are using pads soaked in a 60% solution of formic and placed on the
top bars.  As I understand it, three treatments 6 days a part are required for
tracheal mite and 6 treatments 6 days apart for Varroa. In my opinion, the
this makes  it cost prohibitive for a commercial beekeeper with a lot of out
yards.  The savings in material costs will be eaten up by labor and
transportation costs. That is why I like the Nassenhof dispenser developed in
Germany and available in the U.S. from Betterbee. It wicks the formic right in
the center of the brood cluster and will last three weeks. It has been
extensively tested in Germany but needs to be extensively tested in this
country also to see how it works in the various weather conditions that exist
in our country.