Since there is no peeking in a hive until the outside temperature reaches a minimum of 65 F, one might wonder how honey bees are surviving the winter temperatures like the -18 F to 38 F swing during the January 31 to February 4 weather roller coaster.
“The cluster of bees gets tighter,” explains Dennis McGahan, beekeeper and owner of Mike’s Apiaries in Vicksburg. With 30 years of beekeeping experience, McGahan says he has tried many techniques to winterize his hives over the years and explains how bees cluster to keep warm:
Workers form a mass or cluster to generate and conserve heat
The queen is in the center of the cluster
The cluster maintains approximately a 92 F temperature
Bees generate heat by shivering their thoracic (wing) muscles
Shivering is only one of the jobs to maintain the warmth of the cluster. A layer of bees locks its legs together to form a heat shield of insulation around the shivering bees. Bees do move within the clustered mass, fanning wings to disperse excess heat and regulate carbon dioxide, and the bees will rotate turns to shiver.
What about food? Honey – 60 to 80 pounds of it should be left in the hive in fall to sustain the colony through the winter months. The cluster forms at the lower end of the hive and slowly moves upward as it depletes food stores. By the time spring arrives, the cluster should be near the top of the hive body. Buzzing should be heard by listening to the top of the hive and if it’s 65 F or warmer, a visual inspection will alert the beekeeper to a successful overwintering…or not.
It’s also interesting to note that in January, the queen begins to reproduce and both queen and brood are the priority for the workers to keep warm. Food is the colony’s fuel and it needs to be available to the bees at all times. It’s better to leave too much food than too little.
Beekeepers also use insulation techniques such as tar paper or Styrofoam in late fall to give the bees extra help to maintain 92 F throughout the winter months. Much is written on the subject with varying opinions and experiences. Ventilation in the hive is also very important to disperse moisture. Honey bees have a number of issues that can weaken or kill them and moisture is one of them. The heat they generate in their cozy clump rises to the top of the hive, forming moisture that can drip back down on the cluster if the hive isn’t properly ventilated.
“Thirty years ago, we didn’t insulate hives,” notes McGahan. “We didn’t need to.” He believes decades of sublethal exposure to pesticides have weakened the honey bee and decreased the population of other insects like the monarch butterfly.
With only a few more weeks left of winter according to the calendar, honey bees should be nearing the end of “shiver season,” getting a potty break on a sunny day that reaches 45 F or higher, filling their bellies with plenty of their own food still on hand, and looking forward to gathering pollen and nectar in spring.