First off, my thanks to all the people who commented on the idea of looking
for mite resistance in swarm queens.
 
Wayne brings up two good points about swarms:
 
      How do you know they are truly from a wild colony?
 
      How do you keep them from infecting your other colonies with Varroa?
 
As to the the origin of swarms, although you can't completely prove a swarm
to be from a feral colony (unless you saw it come out of a hollow tree), you
can make a good guess (especially in my suburban Maryland location).   First,
is the swarm queen marked?  Second, are there other beekeepers near  where
you collected the swarm (within a mile)?   I daresay that any swarm that
comes with an unmarked queen and from an area you know to be devoid of
beekeepers has a high probability of being from a wild colony.
 
As to totally preventing Varroa spread via drifting from the swarm colony,
there will always be drifting in a multicolony apiary.   It would be nice to
be able to set up a "quarentine apiary"  for  swarm colonies, but for most of
us that would not be practical.   However, considering that all my colonies
have tested positive for Varroa for the last three years, I don't worry
abouta swarm colony introducing Varroa to my other colonies.   It's already
there.
 
Allen made the comment that some professional scientific guidance on this
project would be advisable, and I agree.   One of the banes of small-scale
research projects like this one is trying to get enough data and enough
control over the experiments to make the results something more than
interesting anecdotes.   If last year was any guide, I will be lucky to even
catch a swarm this year.   Nevertheless, I will discuss the professional
guidance issue with our State Extension Apiculturist and see what ideas he
has (Gordon -consider yourself warned).
 
And lastly, the Coppalas mentioned the long odds against finding a strain
that is both Varroa and Tracheal mite resistant (using their figures, perhaps
ten colonies in Maryland would show resistance to both mites), and also the
concern that if I did find such a colony, the local drones from nonresistant
colonies would wipe out the valuable traits when they mated with any new
queens.   These comments I can only answer with the observation that amid all
the mite carnage, some bee swarms still appear every April, and in areas
where I don't know of any local beekeepers.  Somehow, the wild colonies that
produce these swarms are prospering.   I'd like to know why.
 
Keep those comments and ideas coming in, especially if you are a professional
researcher interested in organizing this work.   I daresay the organizing
could be done by e-mail.
 
W. G. Miller
Gaithersburg, MD