Hi Greg,
 
I tried your personal email address and it didn't work, so I'm posting it
on the the BeeL.
 
Hopefully this information will be of some use to a lot of you.
 
You should be able to see a color difference between the two different
races.  The Italians should be yellow and the Carniolans should be black.
The Carniolans probably have some yellow workers because of miss matings,
but most of them should be pretty black.  You should be able to see a
difference when the bees start preparing for winter.  The Carniolans stop
their brood rearing earlier than the Italians.  There should be a
difference in the spring like you said, since carniolans over winter better
than most Italians.  I don't know how all uses NWC's, but they should do
fairly well in the VA/NC/TN area.  I have heard from Dean Breaux from
Hybrid-Bees that the Carniolans don't do to well in his area in Florida,
compared to the Starline Italians that he uses.
 
By all means treat your bees for both mites.  The NWC's keep the mite
levels down to a minimal level comparable to the Buckfast, but they are not
resistant to tracheal mites just tolerant of them.  There is also a degree
of variability in the stock, some have high mite levels while most have low
levels.  Here at Ohio State we only treat for tracheal mite with grease
patties and have had very low loses the last couple of years despite the
severe winters.  We are also looking at hygienic behavior as a possible
mechanism for lowering the levels of vorroa mites in the hive.  This
project is in cooperation with Marla Spivik at Minnesota.  She has been
able to show that colonies bred for a high degree of hygienic behavior
remove more vorroa mites from the cells of capped pupae.  But wether this
significant enough to drastically drop the vorroa mite population in the
hive is unknown right now.  Because the hygienic behavior has proven to
help lower brood diseases in the hive, we are now starting to increase the
degree of this trait in the NWC's.  This will be a slow process (three
years maybe), because the genes responsible for the hygienic behavior is
only found in 10% of the colonies in a non-selected population it makes
since to select a little heavier on this trait and increase it over time
than to just select for one trait.  This will help maintain the integrity
of the NWC population of gentleness and honey production and increase
hygienic behavior along side.
 
I have tried Italians and Buckfast along side of the NWC's.  The Italians
scare me too much, they brood up and form large colonies early and will
starve themselves if the are not monitored.  The Buckfast that is available
in this country is so crossed bred with the Italians that their is not much
difference in the two.  The Buckfast has been maintained be Natural Matings
in a predominantly Italian area in Texas for years, no way to control the
matings of the queens.
 
Garrett