> Allen, you mentioned 110 lbs as being a minimum weight for winter. Well, I've weighed all my hives for the last 25+ years. I've adjusted my target weight up over the years so I have only a handful of starved colonies in the spring. In my area, a colony that only weighs 110 pounds would surely be dead before spring

Actually, as my wife says, I have "turtle recall.   

I remember everything -- eventually.

When I wrote 110 lbs, I was scratching my head, since I knew that 90 lbs was sure to starve, and 110 lbs was quite marginal, but also remembered clearly that we used 55 kg as our cutoff in later years and often had feed left over in spring, sometimes even to excess when we used dark bees. 

Somehow, I was thinking (or not thinking) that 55 kg = 110 lb.  

Wrong.

During my lifetime, here in Canada, we switched from English to metric.  We now use metric and the US uses English measure. Some of us are always using both.  See also http://en.wikipedia.org/wiki/Gimli_Glider

We used 55 Kg as our fall weight cutoff, measured in late October   I know that well, and we had great wintering success.  The conversion from Kg to lbs is 2.2, roughly, so *our* cutoff was actually 121 lbs, not 110, and also measured in mid to late October after there had been some weight loss already.  My scale hives are currently losing roughly 0.375 lb per day, so from Oct 1 to today, one can roughly estimate that hives lose 0.375 x 30 ~= 11 lbs/ month in the fall and that should be figured in, too.

That said, I still do recall that 110 was still a *minimum* minimum, but getting quite risky and 90 was bound to starve. We used English measure back when I learned that in my early years -- the hard way -- and I also remember those numbers quite well.  As a note,when getting that close to the line, the weight of covers, floors, etc become significant in comparisons, but can be somewhat ignored when weights are much higher.

When I wrote, I was assuming (also risky) that our winters are quite a bit colder and longer on average than the area in question, so figure the 110 should still be a safe MINIMUM there, but as always, YMMV.  I was guessing. I always weasel a bit, too, and always say, "Be sure to consult someone local if you can".

All that having been said, aiming for the minimum is never a good plan since, as we have discussed here repeatedly, light hives eat their pollen early, fly around a lot all fall, wearing themselves out, and are at risk of partial starvation during winter from lack of feed overhead or nearby.  Additionally, they are a worry in spring, especially if there is aheavy late snowfall and the beekeeper cannot get to the yard because, once brood rearing gets going, bees eat a lot and can starve very quickly.

Hives going into winter at the minimum, no matter what that number might be locally will never perform as well as hives that are heavy going in.

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