Upper Entrances

Another great cause of loss in winter is improper ventilation, or no ventilation at all. Every swarm of bees throws off a considerable amount of moisture from their bodies. In very cold weather, if the hive is not properly ventilated, this moisture collects on the combs at the sides and top of the hives in the form of frost and ice. In moderate weather this frost and ice melts and runs down into the hive, completely saturating the bees, and then, if a sudden change to extremely cold weather takes place, all are destroyed by freezing. —Lizzie E. Cotton, 1891

By wrapping the hives with black tarpaper or building paper and or the use of upper entrances, the moisture in the hive can be greatly reduced. The black or dark surface color of the paper will absorb the heat from the sun and warm the walls of the hive, thus driving off the moisture and it will be circulated out of the hive either through the upper entrance, if there is one, or the lower entrance. The main purpose in using the upper entrance in region is not only for ventilation to reduce the humidity but also provide an air vent to the outside which is storm and Ice proof.—Virgil Raymond Bayles, 1953

The clustered bees generate heat through the metabolism of honey. Upper entrances to allow moisture, resulting from the metabolism of honey, to escape from the hive were advocated by Conner (1940), Farrar (1943, 1952) , Dadant (1942), and Gooderham (1940). Baker (1942) demonstrated that colonies wintered more successfully with upper entrances than did those with no upper entrances. Provision of upper entrances has become standard practise for outdoor wintering. Figure 5 shows ice buildup within the hives resulting from condensation of moisture-laden air due to a lack of ventilation. These colonies were not prepared to endure sub-zero temperatures since they were not insulated and did not have upper entrances to allow for some ventilation.—John Michael Gruszka, 1979

The best way to vent extra moisture from wintering colonies is with an upper entrance. This entrance is VERY IMPORTANT! A study from northern Alberta, for example, demonstrated that either a 1 x 1.5 cm top entrance built into the inner cover or a 2.5 cm diameter hole in drilled into the middle of the upper brood box greatly increased colony strength, health and decreased the consumption of honey stores (Fig. 7).  Cold air does not hold as much water as warm air, so as warm moist air leaves the cluster, it condenses on the comb. Bees can cope with some moisture outside the cluster, but if the moisture accumulates and begins dripping back on the bees it saps them of heat. This issue is significant when we consider the role of the upper entrance in your colonies.— Adony Melathopoulos, 2007

Beekeepers in the far northern states and Canada may wrap colonies to reduce wind infiltration and to warm the hive on sunny days. Hive entrances must be open on both the bottom upper hive entrance for ventilation. — James D. Ellis and Katherine Hammons, 2013

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html