While my losses were a minimum, those around me had huge losses. The
speculation on why is only that - speculation. At least in my neck of
the woods, the big losses seem to be from resistant varroa mites.
Beekeepers are telling me there are thousands of mites on the bottom
boards of dead colonies. So, the tracheal mite theory isn't so for my
area.
    And about treating for tracheal mite. I haven't used grease for
several years, and I stopped using menthol ten years ago. Instead, I
rely on tm resistant bees. Ha you say! There aint no such thing. Well,
there is. Scientists have shown this resistance. George, do you remember
the talk as EAS several years ago where they compared TM resistance
among various stocks of bees? They showed how Buckfast and Webster had
significant resistance to tracheal mite. We all know the story of the
Buckfast bee, but what of Webster. Kirk Webster began, in the late 80's,
to raise queens from his best colonies, and winter them in 4-frame nucs.
This was the height of tm deaths. It wasn't long before his tm mite
problems vanished. Just by breeding from his best he was able to develop
a strain of bees very resistant to tm. So, what I'm saying is don't rely
on a bandaid approach. Resistance is the best way to go for tracheal
mite. Now varroa is a different bug all together. Until resistance is
developed, chemical control is the only help - sad to say.