January 23, 2010
In beekeeping circles, plenty of advice circulates about how to prepare beehives so the bees will survive the winter. In purely financial terms, the direct cost to replace a dead colony (or "dead-out") will be in the area of $90 for new bees. By the time a beekeeper receives new bees and the bees start producing honey, the beekeeper will probably miss the benefits of the spring "flow" - the bounty of nectar produced by a rush of spring flowers. The recovering hives won't produce surplus honey until the fall, and the beekeeper has lost half of the year's potential honey crop. That could mean a loss of 100 to 150 pounds of honey per hive or, in grocery-store terms, up to 200 honey bears. The hobby beekeeper may not mind losing out on the spring honey but sideliners -- beekeepers who make a little extra income from their bees -- face a much greater loss from each dead-out.
Preparations for overwintering take place in the fall, for once temperatures drop below 50 degrees, the bees start to form their winter cluster. Colonies die for three major reasons: starvation, freezing and disease.
Disease: Honey bees fend off a variety of parasites, fungi, viruses and bacteria. Very large (or "strong") colonies can frequently survive most of them. Smaller (or "weak") colonies have more trouble. A parasite like the Varroa mite, if not kept in check, can end up killing a hive that might otherwise have survived the winter. Beekeepers treat for various disease in the summer and fall with both natural and chemical techniques.
Starvation: Bees store honey (and pollen) to eat during the winter. They will turn nectar into honey with whatever space they have available to them. As long as the beekeeper keeps adding space to the hive the bees keep making honey. In a good year, and properly managed, bees can make between 300 and 400 pounds of honey per hive.
Depending on local conditions bees need about 80 pounds of honey for the winter. As long as the beekeeper leaves enough honey on the hive, starvation alone should not kill the colony. If the bees could not make enough honey over the summer, then the beekeeper has the option to feed the bees sugar or sugar-based concoctions to help them bolster their stores.
Temperatures: Cold temperatures can devastate even a healthy, well-provisioned colony. If the weather turns too cold for too long, the clustered bees can't move around in the hive to get at their honey. They could starve to death with ample honey just inches away.
Beekeepers get creative when it comes to giving the hive a boost to the internal thermostat. Placing the hive in a good location comes first. This is where understanding local weather conditions helps. Under optimal conditions the hive will rest in a spot that receives winter sun, behind a windbreak, with the entrance facing away from prevailing winds. Even during the winter the hive needs airflow so there is always at least a bee-sized hole in the hive, but the hive doesn't need a 20-degree wind tunnel, either. Converting honey to heat releases water vapor into the hive - if the water condenses and rains down on the bees, the beekeeper might end up with an ice ball instead of a colony. Good air circulation through the hive structure helps eliminate this problem.
For some hives placement may be enough to buffer the hive from the worst of the winter weather. Others may need more attention. Painting the hive a dark color, or wrapping the hive in dark tar paper, allows the sun to heat the hive. Some beekeepers wrap hives in an insulative blanket, which moderates the hive's internal temperature extremes. Others have moved hives into bee sheds where they could keep temperatures cold enough to encourage the bees to cluster, but warm enough that the bees never face extreme cold.
Regardless of the beekeeper's technique, the primary goal is to keep as many colonies alive as possible. No beekeeper enjoys opening up a hive and finding it lifeless. Whether keeping bees for fun, honey or beeswax, a successfully overwintered hive separates a "beekeeper" from a "bee-haver."
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