Ergo, it appears to me that as far as the gradient from extremely little
ventilation to unlimited ventilation, colonies in cold-winter areas in
general do better towards the less-ventilation end of the gradient.


Randy   We have rather dry winters - usually.  43+ years, hives outside and indoors, large and small.  This is what works best for me:


1) Two story hives.  I've made it through with 5 frame nucs, but they take a lot of work in my climate.  I follow our commercial guys rule of thumb - two story with good honey stores, bees, bottom board, and cover should weight at least 120#.  
2) More bees is better.  As Peter found in references, and I was told by our commercial guys and confirmed by my own colonies - about 50% of the bees in each colony will die over the winter - that's a 50% population drop.
3) One of my last conversations with Ed Southwick before he lost his battle to cancer - bees can survive tremendous cold if the bee population is large enough AND the bees have adequate stores.
4) Close the entrances down - that's a must.  I've wintered with and without wraps, with and with wind shields, small and large colonies, and it's really the small bottom entrance that's most important - although I do tend to check to be sure that a pile of dead bees isn't closing it off - if I were to re-engineer the boxes, I'd want a bottom entrance an inch or two above the bottom board.
5) In my climate, I warp in black roofing felt (tar paper).  I fold the top over, so I can open during the Jan thaw to check on food stores, add if needed.
6) I don't use porous insulation or any air-tight wrap like bubble-wrap.  I don't use plastic hives nor styrofoam.
7) If possible, push the hives together (side by side) and wrap the group.


In a normal year, simply closing down the entrances will work, and the bees may propolis  the entrance down smaller.


In a year when our January thaw is followed by two weeks in February of howling, severely cold, winds pouring down from Canada - they'll all be dead if the bottoms are open (e.g., screen bottoms).  It's the same as the engine in my truck.  Go to work, even on a cold day, with little or no wind, and at lunch, the engine block will still have enough heat to easily start.  Go to work on a day when we get frigid winds blowing in from Hellgate Canyon, and the engine will be cold in 20 minutes, and it may not start by noon.


In a year when we get severe cold plus weeks of inversions, little sun; unwrapped colonies may starve on the frames - they don't get warm enough to break cluster and move to frames with honey.  That's where the BLACK wrap makes a difference - just enough warmth to break, move, when there's a sunny  day.  


Don't use any porous insulation - old-timers used to stuff straw between hive and wrap - the January thaw would melt snow, the straw would get wet, then the Feb freeze would put the bees inside a block of ice.


Inner covers - I never use.  In a different climate, I might.  Here, wooden inner covers, when damp, sag in the center, where the slot is located.  That's right over the cluster, so if moisture does build on the inner cover, it runs down onto the cluster.  If I were to use inner covers, I'd arch the board so that the low spots are on the outside, keeping the drip off of the bees.


Lots of bees - I learned this from my mentor in Broadus MT.  His philosophy, the more the better, our  springs come early and fast after the snow.  The more bees in the spring, the faster the colony grows.  He had documentation of some of the largest honey crops in the state.  He even kept a few supers of honey on a pallet in the corner of each yard.  In mid-winter, he'd ski or snowmobile in, check weights, and dig down and get supers to top off light hives.  This is clearly a climate/bloom issue - I find the same, small colonies grow slowly, big ones take off like a shot in the spring - mainly, I assume, because of when the spring bloom hits - BEFORE any more of the over-wintered bees die and as the brood rearing is taking off.  I agree with him, I'll gladly feed the extra bees, it pays off in the following year's honey yield.


Feed - if I feed, it's a semi-dry feed - just wet enough to sort of cling together, easy for bees to eat - NO Hard Candy.   If I have a sudden need to feed, dry sugar on a top shim is better than starving and better than syrup.  Syrup is only used when it won't freeze and i always feed with an inverted feeder on top.  In our cold/cool/cold springs, my bees won't use entrance feeders nor move to a hanging feeder inside the hive - which also adds moisture, besides drowning a lot of bees - which seems worse when its cold.  


HOWEVER, I've also run colonies in just about every region of the US - and what works here in MT would not work in MD or Seattle.  There moisture, not cold is the issue.  Insulation and wraps may intensify the moisture problem.  Unwrapped hive, slotted bottom boards, hive tipped to drain water off of bottom board and out the entrance, and often a top hole or even a shim to lift the cover a bit works best.  I once heat-stroked a couple of colonies in a 20 minute move in MD - the dead bees were sopping wet - not  enough ventilation.


For years I had a year-round, 5 frame observation hive in my office with a bottom entrance tube (opened in bottom, center of hive) run to a south window.  Most days, the bees in winter clustered (yes, even in a warm office) over a frame of honey.  But, if the wind was blowing, they'd be on the side of the hive closest to the window - the wind was coming through the tub and there was a cold draft on the side opposite the tube entrance.  On sunny days with no wind, they'd be over on the far side taking advantage of a bit of cooling.


Finally, our IR cameras clearly show that on very cold days, if they've adequate honey stores, the bees from adjacent hives tend to move so as to share a common wall - obviously sharing warmth.









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