Further investigations on the value of electric heating of beehives

Abstract

A set of twenty‐four colonies of honeybees was divided into three groups, two of which received different intensities of artificial heat, applied by means of specially designed heating frames placed in the middle of the brood chambers, from 2 Jan. to 16 Mar. 1942. Heating the colonies reduced the area of brood present at the beginning of May without noticeably affecting the consumption of carbohydrate stores and thus had an adverse effect on the colonies. This conclusion is in agreement with that reached as a result of earlier work (Butler & Cockbill, 1942.)Colonies in hives fitted with top entrances were no stronger in the spring than colonies in hives with bottom entrances, nor did they show any significant difference in store consumption.No significant brood chamber temperature differences were found in hives fitted with top entrances as compared with control hives which had normal bottom entrances.During the period when heat was applied to the colonies by means of the heating frames the minimum brood chamber temperature was significantly higher in the heated hives than in the control, unheated, hives, this being especially marked in the case of the hives fitted with 6 W. heaters.Throughout the experiment the minimum brood chamber temperature of all the hives showed a close dependence on screen temperature. During the preliminary period before the heat was turned on a change of 1d̀ C. screen temperature was associated with change of 0.92d̀ C. in the minimum brood chamber temperature in hives with top entrances, and a change of 0.86d̀ C. in hives with bottom entrances. After the heat was turned on the corresponding figures were 0.84d̀ C. for top entrance hives and 0.67d̀ C. for the bottom entrance hives.