This is my first winter with bees.
 
setup
I live in southern Quebec , about 20 miles from the New Hampshire border
in USDA zone 4.  This fall I fed my 2 hives fumagillan medicated syrup,
covered the hives with black fiberboard and as per Richard Bonney I
inversed the inner covers and added fiberboard on top to absorb the
condensation and also provided ventilation. I placed a 3 foot high wind
break 10 feet behind the hives on the NW side.  The weather has been
relatively mild recently, -4 to 0 degrees C(30 to 36 degrees F)with no
wind.
 
problem
This morning I found the bottom boards covered in dead bees and other
dead bees scattered in the snow in front of the hives.  I even found the
odd bee 10, 20, 30 feet in front of the hives.  When I approached the
hives I seen 2 bees fly out and off in the distance as if to forage (-4
degrees C and overcast).
 
What gives?
 
Michael