Colony strength and condition

A colony population of adequate strength for winter is a prime requisite. At the close of brood rearing in November, a colony of suitable population should fill at least two standard 10-frame hive bodies from wall to wall and top to bottom at a clustering temperature of about 40° F (4. 44° C).

Smaller colonies should be united, and only first-class colonies should be overwintered. A poor policy is to attempt to overwinter subnormal or weak colonies, because they seldom will survive. Weak colonies that perish in late winter or early spring probably will be laden with nosema disease. As they are dying, they defecate nosema-laden feces on the combs and equipment, adding difficulty to replacement with package bees. The potential winter loss is best taken at the start of overwintering to keep the equipment clean and conserve honey. In the spring, strong, overwintered colonies can easily be divided and colony numbers doubled or trebled.

The age of the bees going into winter is as important as population size. Late summer and fall brood rearing should be encouraged. This can be accomplished by using young queens and providing ample pollen and honey. Young queens of the current year will lay eggs later into the fall than old queens.

An adequate pollen supply in late summer is necessary to support this late brood rearing, and in most areas pollen is usually available. If a colony has a poor, old, or failing queen, or if the bees have been queenless for a prolonged period in late summer, the population may have a higher than normal proportion of old bees as it goes into winter. When this situation occurs, the population size may look adequate in late fall, but, as winter progresses, the population may shrink faster than winter brood-rearing can compensate, eventually resulting in a colony loss. Such weak colonies may become still further weakened by nosema disease and may perish.

Two tests conducted at Madison, Wis., illustrate the effect of late fall brood-rearing on overwintering success and honey production the following season. At one location, groups of 12 to 13 colonies each, all of the same hybrid stock, were used in tests in which brood-rearing was curtailed early and late by caging queens at different intervals. Queens of one group were caged on August 15, a second group on September 15, and a third group on October 15; the queens of the fourth group were not caged. All queens were released on December 15. The same test was repeated the next winter using groups of 11 and 12 colonies, all of the same hybrid stock. In this test, all queens were released on November 15.

Table l-Effect of early termination of brood-rearing in the fall on honey production the following summer, Madison, Wis.

Average gain

Colony losses April

1 Number (in parentheses) of colonies represents the average.

In March when pollen supplement was fed, colonies with queens caged in mid-September and those caged in mid-October had good populations. Those with August curtailment of brood-rearing were noticeably weaker. After brood-rearing expanded in May, these relative population differences persisted.

Final production records for normal colonies in each of the test groups are shown in table 1. The caging of queens in October near the normal cessation of brood-rearing had less effect than caging of queens in August or September to terminate brood-rearing. Cessation of brood-rearing in August, September, and October resulted in corresponding reductions in production the following summer, depending on how much fall brood-rearing was prevented.

Where queens were caged in August, colony losses over winter were high-10 of 13 the first winter and 6 of 12 the next. Later caging showed correspondingly less winter loss.

Young, vigorous queens must be present in late summer. Any colony showing poor brood quality or quantity should be examined closely for possible queen replacement. Poor queens are often replaced or superseded by the bees in late summer without the beekeepers intervention, but for best results the beekeeper should be alert to the possible need to requeen. A regular requeening schedule is a part of good management.

Some stocks rear brood later than others. This stock characteristic, along with a heavy or compact brood nest, makes certain strains of bees more or less suited for overwintering.