Wintering bees outside in the North is somewhat complex, however, we have always wintered our full hives outside and average about 10% mortality per year. Some years, we have exceptional success with wintering, and lose less than 5% of the hives from our apiary. Other years, the losses can be up to 30%. To keep bees alive during the Manitoba winters, the bees need to be disease free, and the mites need to be under control. Additionally, the bees need to have sufficient winter food stores. We try to get 6 gallons of sugar syrup (66% sucrose) into our single hives in the fall.
All hives are fed in the fall and are packaged into their wintering positions when the bees cease flying for the year. This happens when minimum nighttime temperatures fall to -10C (14F), and daytime temperatures stay below 0C (32F). During a warm day, some bees might take short flights through the upper entrance.
For a number of years, we have used The Bee Cozy - Winter Hive Wraps obtained from NOD Apiary Products in Ontario. These winter wraps have worked very well for us, and we continue to use them in our apiary. They are easy to use, and require require very little work to apply in the fall, and clean in the spring. For a good photo sequence of someone using The Bee Cozy - Winter Hive Wraps, see the instructions provided by Lance Waldner.
The hives stay in the winter packaging until temperatures have warmed sufficiently and the average nighttime temperature stays above freezing. Sometimes, when the hives are too crowded with bees, they have to be unpacked prior to the optimum period so that a super can be added to give the bees additional room.