Bob Billson asks about a colony which apparently absconded from the hive
during late winter, about making splits, and care of the hive.
 
Bob, you don't say what the level of Honey Bee Tracheal Mites (HBTM) were
in the two colonies in the fall, or what your observations were in
September and October before the weather became cold.  You say the Italian
colony was active in early February, does that mean you removed the hive
cover to see how many bees there were?  Without this information there are
three possible explanations from my experience:  One is a high level of
HBTM, the second is queen loss, and the third is bee genetics i.e. bee or
colony behavior.
 
1.  Usually with high levels of either HBTM or Varroa the colony
collapse/absconding occurs in late summer or early fall when supers are
removed.
 
2.  Queen loss.  Quite often these days a high percentage of new queens are
lost by fall and in many cases the bees make no effort to supercede them.
If the queen was lost in mid August the bees could have moved over to the
remaining hive, over a period of several weeks.  You didn't mention any
robbing of the honey in the empty hive which leads me to presume that it
didn't occur.  This means the colony collapse probably began, or occurred,
later in the fall to early February, when robbing doesn't occur.
 
3.  This is the most likely cause:  bee genetics i.e. bee or colony
behavior.  Between 10 and 90 percent of new queens (average 30 percent),
and packages, exhibit what I have been calling aberrant behaviors.  These
include a lack of queen retinue, "noisy" colonies, runny bees, a failure to
cluster in the proper shape at temperatures in the 50s F., all of which
result in the colony's failure to winter.  There are other aberrant
behaviors but these are the most easily recognized.  In a few cases, when
there are only low levels of these aberrant behaviors, the colonies may not
finally disappear until early spring.
 
In my own experience over the last 12 years these behaviors have caused 25
to 30 percent colony losses (exactly as you describe) though I have
purchased queens from at least as many sources.  My HBTM levels have been
around 10 to 15 percent, and Varroa counts between 50 to 450 per colony in
mid August.  Apistan was used when the honey was removed.  The colonies
were three to four westerns (2 + deeps) full of bees in late September, but
after two weeks of cold weather (40s down to 30s F.) these aberrant behaved
bees disappeared from the hives in early to mid October.
 
Don't worry about the mold in the hive.  A new colony will clean up the
combs.  If you had the proper amount of top ventilation, excessive moisture
shouldn't have been the cause of the mold, just no bees to keep the hive
properly ventilated.
 
I would suggest waiting until your queens come to make splits.  Let your
remaining colony built at its maximum rate until then.  You may even find
it necessary to replace last years Buckfast queen, judging by local
beekeeper experience here.
 
To all BEE-Lers:  It would be quite helpful if you give us the number of
combs of bees (deep or westerns) in hives when you are describing a problem
colony and when comparing it to a "good colony."  The size of the colony
cluster is extremely important in making a diagnosis because it is a
variable which often easily suggests the colony quality and maybe queen
quality for the time of year.
 
James C. Bach
WSDA State Apiarist
Yakima WA
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