This is just some quick advice in response to Brian Hensel's experience with
re-hiving a colony in abandoned equipment.  It sounds like Brian did a good
job in trying to clean up the mites and Nosema, but I would suggest that
people in this situation shoud not requeen. If those bees represent a colony
that survived on its own for years rather than a recent swarm, they may have
some resistance to mites by natural selection.  From the description, it
sounded like they had good hygienic behavior which helps bees resist many
brood diseases (like Varroa).  Unfortunately, one loses the genetic stock when
requeening.  Consider letting the bees raise their own queens, or raise queens
yourself.
 
Greg J. Hunt
Honey Bee Specialist
Dept of Entomology
Purdue University
West Lafayette, IN