An interesting two part paper entitled "Rethinking Our Ideas About the Winter Cluster" appeared in the July 1998 edition of the American Bee Journal. Data was obtained from hives over wintered in various configurations such as large cluster size, extra hive wall insulation, etc. Metabolic rates were also obtained from caged bees at different ambient temperatures. The importance of a "water balanced economy in an optimum size colony" was proposed as a major factor controlling winter cluster behavior. This idea explains much of the personal observations I have had overwintering bees both indoors and outdoors in dry, cold climates such as Wyoming and interior Alaska. It could explain some of the behaviours attributed to temperature. The bees efforts to limit upper ventilation may be an attempt to control water resources rather than retain cluster heat . In climates that would provide the winter cluster with sufficient water resources through humidity, frost accumulations around the cluster or outside flight activity, the impacts of upper ventilation and water balance may not be so apparent. The importance of water balance to the winter cluster was also demonstrated by a Canadian beekeeper during the 1970's. He used water vapor to initiate brood rearing in indoor wintered colonies and sold the extra early production as packages. He wrote a series of articles for the American Bee Journal. I have lost the references. Sorry! During the spring the factors that provide an optimum hive environment are drastically different that those during the winter. Wrapping, ventilating or insulating a hive during one season could provide the optimum environment for the bees. During a different season the same treatment could kill or weaken the hive. Best Wishes Dennis Murrell