By Patricia Donahue, volunteer apiarist
Our honey bees worked hard this year and because of that, we benefited by being able to harvest some delicious honey in August (which is for sale in the GHM gift shop, while supplies last). A female honey bee (worker bee) will live about 6 weeks in the summer and each worker bee makes approximately 1/12 of a teaspoon of honey in her lifetime. If each bee makes 1/12 of a teaspoon of honey in her lifetime, and there are 6 teaspoons in one ounce, it will take 72 bees to produce one ounce of honey and 576 bees to fill an 8 ounce jar of honey! Our bees work hard making honey for Golden History Museum and we want to make sure we take good care of them all year, especially during the winter.
Overwintering a honey bee colony is one of the most difficult tasks for the beekeeper, especially in Colorado where the temperatures can be 75 degrees Fahrenheit one day and below freezing with 5 inches of snow the next. This year, we’re using a different technique to keep our honey bees warm in the winter and reduce the added stress winter creates for them.
Bees in nature typically overwinter in tree cavities which depending on thickness, can provide good insulation. When we compare this to a hive box (like those at the Park), the bees must expend a tremendous amount of energy vibrating their flight muscles to stay warm enough to survive cold temperatures with the thinner walls. If you overwinter your bees with no added insulation, the bees will likely not survive the winter, because they will either freeze or starve to death. So, what can beekeepers do to decrease colony stress and losses over the winter? Provide the bees with some type of insulation! This year at the history park we are using the Hive Hugger to keep our bees warm. This is a condensing hive system created by Minnesota beekeeper Peggy DeSanto. Her design was the 2023 winner of the American Beekeeping Federation, Innovation Award.
There are two basic camps when talking about how to over winter honey bee colonies: the ventilating system and the condensing system. There are several principles that come into play with each such as thermoregulation, condensation, moisture, and air flow, but today we will just cover the basics of each.
The ventilating system involves wrapping the hive boxes with an insulating material. An insulating material such as polystyrene is placed on the underside of the top cover. The lower entrance to the hive is turned into the smallest opening and an upper entrance on the top box is left open to provide ventilation, allowing the air to come in the bottom entrance, flow up through the hive boxes, and out the top entrance. While this system provides ventilation for the bees, it also allows the heat to escape and allows moisture to collect on the underside of the outer cover. A moisture board or quilt board with an absorbent material such as wool or wood chips is sometimes added between the bees and the outer cover to absorb the moisture, so it does not drip on the cluster of bees below. Bees can survive very cold temperatures, but they cannot survive if they get wet.
The condensing system also involves wrapping the hive boxes with an insulating like the ventilating system, but the insulating material under the cover is thicker. The lower hive entrance is turned to the medium setting and all upper entrances and openings are closed off and any gapped seams are taped so the only air flow coming into the hive comes in through the bottom entrance. By insulating the hive as described above and creating a bottom only air flow, the space above the bees will remain above the dew point [1] and condensation will not occur there. Instead as the air rises from the bottom, it warms as it passes through the wax comb and the bees, and in the warmer space above the bees, the air spreads to the cool air along the side walls before condensing. The water then runs down the side walls instead of dripping on the bees below.
Bees generate heat in two ways: activity and exhalation. The heat created by exhalation is latent heat which the condensing hive retains. So, by allowing the warm air to condense within the hive and in the correct area (the side walls) there is a dual benefit of retaining the heat the bees generate from both activity and exhalation. The environment being created in the condensing hive is driven by bee biology wherein the bees are controlling their climate – including humidity, temperature, and air flow within the hive and around the colony. By contrast, it is the beekeeper that is trying to control the climate in the ventilating hive by adding more ventilation at the top of the hive box and absorbent material to collect the water that condenses above the bees. In most cases, the bees know what they need better than the beekeeper does, and the bees seem to be telling us that they like the condensing hive systems better.
[1] the temperature and pressure at which the first drop of water vapor condenses into a liquid.