As always, George Irimie's (GImasterBK) thoughts were well worthwhile.  I
wish I had his knowledge and beekeeping record!  Since he invited me to
expand my response concerning winter loss in the colder climates, I will do
so.

Thankfully, we do have resistant (or tolerant?) queen breeding stock.  As
others have mentioned, Kirk Webster of Champlain Valley Bees (802-758-2501)
has developed such stock.  While he is sold out for 2000, his stock has the
advantage of being open mated.  Resistant stock that is more generally
available is the New World Carnolian strain developed and maintained by Sue
Cobey.  At http://iris.biosci.ohio-state.edu/honeybee/breeding/index.html
you can find her data on tracheal mite infection for the past several years.
(Once at the site, click on New World Carnolian, and then on Stock
Evaluation Protocol.)  Both Sue and Kirk suffered huge losses from tracheal
mite and then rebuilt their stock from survivors.

Sue counts her tracheal mite infection rate every spring and reports the
result.  It has been running 2%-7% for the past several years.  However,
this count may come from instrumentally inseminated stock, which most of us
are unlikely to buy.  (And in contrast to Webster's open-mated stock.)  All
I can say is that I have purchased open-mated New World Carnolians from
California breeders for the past 10 or so years, and I have few tracheal
mite losses.

During 1999-2000 I over wintered 61 colonies.  I had only one dead colony
this spring, but had four very weak colonies.  I think all of the very weak
colonies were due to tracheal mite infections, as I detected almost no
Varroa drop after inserting new strips.  1999 was the third consecutive year
that I did not treat with grease patties or anything else for tracheal mite.
I look at my losses as part of an on-going selection of  tracheal mite
resistant or tolerant stock.

That said, if I were a hobbyist with something like six or fewer colonies,
so that each was more precious than one of my colonies, I would treat with
grease patties.  They work, and they are cheap and easy to make.  See the
instructions in Dadant's catalog.

Finally, these observations and comments only apply to beekeeping in the
northern part of the country.  For reasons that I forget, tracheal mites are
a far more serious pest in the warmer parts of the country.


Lloyd
Lloyd Spear, Owner, Ross Rounds, Inc.  The finest in comb honey production.
www.rossrounds.com