The winter of 2010-2011 was not a terribly hard one by Michigan standards. The lowest night time temperature that we saw was only about -13 degrees F. What set this winter apart from the average was the lack of a significant thawing period. Typically, in January or February, we have a thaw that brings us a few days of sunshine, accompanied by temperatures in the upper 40s or even the low 50s. That did not happen. We did have some warm weather in late December that melted most of our snow, but those days were accompanied by rain, drizzle and fog that kept the bees inside. The result of these weather conditions was that most bees that were overwintered in this region were dead by the time spring arrived. There was a survey taken by the Michigan Beekeepers' Association that was reported by the local NPR stations. Their findings; small scale beekeepers (those who did not take their bees out of state for the winter months) lost all of their bees, or were lucky enough to have one out of ten hives survive.
You see, healthy bees absolutely will not defecate in the hive, so they need to take flight in order to do so. As was explained in the news story, the bees simply died of dysentery due to the fact that they were confined to their hives for over four months, unable to take even one cleansing flight. We hoped so much for a thaw, knowing that just one cleansing flight could carry our bees through until spring, but it didn't come. The result was that we lost 35% of our bees, something that we found very disparaging until we realized that most others had lost all of theirs.
It isn't rocket science figuring out why most of our bees survived while so many others' bees didn't; common sense tells us why. The fact is, it wasn't us who realized how to let bees survive the most severe winter weather conditions, it was Emile Warré. At least 70 years ago, he knew how bees could survive even the worst winters, and it is to him that we give all the credit for the knowledge.
In a Warré hive, bees can stay warm and dry with minimum stores. This is significant because hives that are too large, and/or are designed in such a way that they require lots of ventilation in order to prevent moisture build-up, cause the bees to consume large amounts of stores in order to keep warm.
Think about your own house for a moment. Could you stay warm and dry in your house if all of the windows were cracked open? Sure you could. But what would that require? Lots of energy, right? Your furnace would run constantly! But your house doesn't work that way, does it? Typically, excessive moisture from things like cooking, taking showers, doing laundry, etc., is mitigated into the attic and then vented to the outside. In this way, you stay warm and dry in your home without the excessive consumption of energy. A Warré hive works in much the same way.
And just as Warré hives are similar to our own homes, bees are similar to us. The more food we consume, the more we must relieve ourselves. It is the same with any living creature. If bees must consume large amounts of honey in order to stay warm in their hives, they must make cleansing flights more often. If they are unable to do so because of the weather, they get dysentery, make a mess out of the hive, and then die. It's that simple.
Our Warré hives, made from cedar to dispel moisture, insulated with a quilt box, and sized so that the bees can more easily stay warm, are the reason that most of our bees lived when so many others died. The surviving colonies overwintered on only about 25 lbs. of stores, not the 100+ lbs. required in other hives. It is largely because of this that they lived through the long, unforgiving winter of 2010-2011.