Winterizing a beehive prepares a colony to survive the cold, resource-scarce months until the spring nectar flow begins. This preparation ensures the colony’s health, protection, and access to necessary resources. Successful beekeeping relies heavily on proper autumn management, as the colony’s ability to cluster, generate heat, and conserve energy affects its survival. The goal is to minimize stress factors like cold, moisture, and starvation, which are the primary causes of winter colony loss.
Structural Modifications and Weatherproofing
Preparing the hive structure involves physical adjustments to create a favorable microclimate for the winter cluster. The lower hive entrance should be reduced using an entrance reducer. This smaller opening helps the bees defend the hive against intruders and reduces the amount of cold air entering the structure. Installing a mouse guard is a non-negotiable step to prevent rodents from entering the hive, where they could nest and destroy comb while the bees are tightly clustered.
For colonies in colder climates, beekeepers often apply external insulation, such as rigid foam boards or specialized hive wraps. This insulation helps to stabilize the interior temperature by minimizing heat loss to the exterior environment. While the bees generate their own heat within the cluster, insulation reduces the amount of honey they must consume to maintain their core temperature. The removal of empty honey supers is also important to reduce the overall volume of the hive.
Ensuring adequate top ventilation is an important structural modification. As the bees consume honey, they metabolize it and produce warm, moist air that naturally rises. Providing an upper entrance or ventilation shim allows this moisture-laden air to escape before it can condense on the inner cover. This mechanism facilitates airflow and prevents the buildup of damp conditions inside the wooden boxes.
Ensuring Sufficient Winter Stores
Colony survival through winter depends on a sufficient supply of stored honey, which acts as the fuel for the winter cluster. The required amount of honey varies significantly by climate, ranging from 40 pounds in milder southern regions to 90 pounds or more in far northern states with long, cold winters. Beekeepers must assess these stores in the late summer or early autumn to ensure the colony has enough reserves. This assessment is often done by “hefting,” or physically lifting, the hive to gauge its overall weight.
If the colony’s stores are insufficient after the final honey harvest, late-season feeding is necessary to build up reserves. This is typically done using a heavy sugar syrup, mixed at a ratio of two parts sugar to one part water (2:1). This thick concentration mimics honey and is easier for the bees to process and store as winter feed, since it requires less evaporation. Feeding should cease once temperatures drop consistently, as the bees may not be able to effectively process the liquid.
Beyond liquid stores, beekeepers should prepare emergency food sources for late winter or early spring, when the risk of starvation is highest. These supplements, such as sugar bricks, fondant, or candy boards, are solid forms of sugar placed directly above the cluster. These non-liquid foods are accessible to the bees when temperatures are too cold for them to break cluster to reach perimeter stores. A colony must also have a sufficient population size, generally 18,000 to 20,000 bees, to form a tight cluster. This strong population is necessary for the bees to collectively vibrate their flight muscles to generate the required heat.
Mitigating Winter Threats (Pests and Moisture)
Excessive moisture and late-season pests are the two most significant threats to a clustered colony. As the bees consume honey, their respiration produces substantial water vapor that accumulates inside the hive. When this warm, moist air meets the cold inner cover, it condenses and can drip cold water onto the cluster, chilling the bees and leading to colony death.
Active moisture management utilizes absorbent materials to capture condensation before it harms the bees. A common method is using a moisture quilt box placed above the inner cover, which is a shallow box filled with absorbent material like wood shavings or sawdust. The material absorbs the water vapor that rises from the cluster, keeping the bees dry. This method works in conjunction with the upper ventilation to manage the several gallons of water a colony can produce over the winter.
Controlling the parasitic Varroa mite is another late-season necessity, as the mites feed on the developing “winter bees” that are physiologically distinct and have longer lifespans. Mite treatments are ideally performed in late summer or early autumn to protect these winter bees before they emerge. A final treatment, often using Oxalic Acid, is highly effective when the colony enters its broodless period in mid-to-late winter, as the mites are exposed on the adult bees rather than hidden within capped brood.