Hi Mary,
 
Your question of the different "strains" of carniolans that are found in
the U.S. is a good question that needs to be discussed.  First off I have
to tell you that I am biassed in my opinion on which strain I like the
best, just like all the queen breeders you talked to.  I work with the New
World Carniolans at The Ohio State University where we are part of a
cooperative breeding program with some queen rearers in California.
 
Carniolan is a race of the honey bee just like Italian, and Caucasian.
Starline, Midnite, Buckfast, Yugo's, New World, Old World, Hastings, ect.,
are all strains of these of these and other races.  All of theses strains
are named by breeder to separate it's identity from the other breeders
"Italian".
 
The Buckfast bee is a strain bred in the Buckfast Abbey in England.  It is
a mixture of many different races of honey bees from around the world.
This bee is a very good general strain.  It produces a good crop of honey,
is very tolerant of the Tracheal mites, and gentle.
 
The Yugo's or ARS-Y-C-1 (official name) Carniolans, are a strain of
carniolan imported from the Yugoslavian Republic by the USDA.  This strain
was bred for Tracheal mite and Vorroa mite resistance.  When first released
it displayed the typical carniolan traits, over wintering in small
colonies, intensive swarming, quick build-up.  I did not find it to be
consistently gentle though, on a nice clear day they were fine but if it
got cold, cloudy, ect.  they could get very aggressive.  The strain
available now is not the pure Yugo.  It has been mixed in with other
carniolan stock here in the U.S.
 
Hastings Carniolans was an imported from Canada.  It is no longer available
in its original form.  It has been incorporated into the New World
Carniolans a couple of years ago.
 
New World Carniolans were started from carniolan stock that could be found
in the U.S. and Canada about 15 years ago.  They were mostly started from
Hastings stock.  This strain is gentle and productive.  Their Tracheal mite
tolerance is similar to that of the Buckfast.  They build up fast in the
spring and shut down brood production early, which helps with the treatment
for vorroa mites.  They are not incline to swarm.
 
The Old World Carniolans were started mostly from the New World Carniolan,
5 or more years ago.  I don't know what they're like because I have only
tried one queen of them.  One queen is not enough to make a fair
comparison.  I can say that it was a gentle colony with a fast build-up.
 
I hope the clears some things up for you.  And it probably generated a
dozen more questions.  Feel free to ask any questions you have that's what
this list is for.
 
Garrett