Walter:
You did not mention treating for TRACHEAL mites.  If your bees were "sick"
from
tracheal mite infection which had become PMS (parasitic mite syndrome), they
could not defend themselves against robbers and just plain died.

Were there many DEAD bees in the hives when you opened them?  Generally, bees
that die of tracheal mite infection die outside because they can't BREATHE
and leave only a small group inside the hive, who can't defend the hive.  The
ONLY killer of tracheal mites is MENTHOL up until this week.  Starting
yesterday, a Formic Acid Gel named APICURE, is being shipped to bee supply
houses that is supposed to kill 100% of tracheal mites, plus 70% of Varroa
mites.

Because they are invisible to humans, many beekeepers just ASSUME that
tracheal
mites aren't around any more, and they lose colonies.

Shucks, you have Dr. Tom Rinderer and Dr. John Harbo right in your back door
at the
Baton Rouge Lab, so ask them about Tracheal Mites.

Just thought I would help.

George Imirie - Beekeeping in Maryland for 68 years and treating against
Tracheal
mites for 15 years, and never lost any of my 100+ colonies to Tracheal mites,
while
neighbors who did not treat with menthol lost many.

I write an awful lot of articles every month about how to UPGRADE from HAVING
bees to KEEPING bees.  They are two different WEB's:

www.cybertours.com/~midnitebee/            click the lower right image
     and
www.beekeeper.org/george_imirie/index.html