Tuesday, December 21, 2010

The Winter Solstice

Honey bees and humans keep different calendars. Today is the winter solstice, the Northern Hemisphere’s shortest day. For us, it signifies the first day of winter and the beginning of the coldest part of the year. However, for the honey bee, today seems to be the start of the new year. With the days lengthening after today, queen bees may restart laying eggs at any time. Many colonies begin brood production on a small scale during the month of January. Most of our hives here in the Arkansas Delta stopped brood production in late October and early November. As a survival measure, the bees conserve food stores during cold weather by maintaining a cooler hive when there is no brood present. Just as we turn down our home thermostats in the winter to conserve energy, the bees regulate their winter cluster at around 70 degrees Fahrenheit. Whenever there is brood present, the bees warm the cluster surrounding the brood to 95 degrees. To warm the cluster of bees to the higher temperature requires the bees to consume a considerable amount more honey.

The honey bee evolved an efficient behavior for maintaining warmth in the hive. Workers only warm the cluster of bees, not the empty spaces around the cluster. The hairy bodies of the bees and the design of the beeswax honeycomb make effective insulation. In cold weather, the bees huddle tightly together; on warmer days, the cluster expands. Bees on the outside of the cluster form an insulating shell; bees in the center generate heat by shivering their flight muscles. Eating honey, a high-energy food, the bees can generate 104 degrees in their flight muscles. The queen remains inside the warm cluster. As bees on the outside chill, they rotate to the center of the cluster. To conserve food, drones were expelled from the hive with the first frost. Today’s photo shows an American bison in Wyoming. These great creatures survive extremely cold winters insulated by a hairy body.

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