If you did a good job of mite control last fall your bees are still going strong. Being February the days are now getting longer. In most hives the queen will have resumed laying. For the hive to successfully raise brood the center of the cluster must be heated to and maintained at about 92 degrees F (just like in the middle of summer). Once brood rearing has started the bees are genetically programmed to maintain the cluster core temperature. Nothing else takes a higher priority. The small patch of brood acts as an anchor for the cluster. This is when some hives get into trouble.
February in Wisconsin can still see extreme low temperatures. Those below zero nights and days cause the cluster to contract in size to maintain the core temperature. In some cases the cluster loses contact with the adjacent honey reserves. With brood to keep warm the bees in the outer edge of the cluster, nearest those honey reserves, must make a choice. Either leave the cluster to get honey or keep the brood warm. THE COMMANDMENT TO KEEP THE BROOD WARM ALWAYS WINS OUT. If the extreme cold spell lasts more than 2 or 3 days the bees will simply starve while keeping the brood warm. If the cold spell lasts only 1 or 2 days and then warms the cluster will be able to expand and hopefully regain contact with the adjacent honey.
All beekeepers doing clean up of deadouts in the spring has seen the classic signs of cold induced starvation. The dead bees are in a tight cluster. Hundreds of the dead bees are head first into the comb cells. Often within inches is a lot of honey.
What’s a beekeeper to do?
-A brood chamber well provisioned with food in the fall is the first priority. Did you provide your hives with fall feeding?
-Strong hives with larger clusters (covering a larger area) tend to weather the cold spells better. That’s something that must be addressed in the fall. Simply do not take weak hives into winter. Combine them with others.
-Emergency food reserves (winter patties or sugar) placed on top of the brood chamber may get your bees through this crisis if they have already risen the top of the brood chamber and are already in contact with emergency food reserve.
-An alternate is the Primorsky Russian bee. Having evolved along the southern edges of Siberia they are genetically programmed to delay the start of brood rearing longer than the European honey bee. Without brood the cluster can more readily relocate.
-Also remember that during pre-varroa times it was common to lose 10-15% of hives; most of which were do to starvation.