Production Research Report No. 169

Agricultural Research Service United States Department Of Agriculture

In cooperation with The University of Wisconsin College of Agricultural and Life Sciences

Abstract

Requirements of overwintering colonies of honey bees are strong, vigorous colonies with abundant winter stores (90 lb (40.8 kg) honey in October) in the proper position in the hive. Winter consumption of honey and its effect on colony yields the following season were calculated for 1, 034 colonies over 8 years and show an average yield of 49 lb (22. 3 kg) more honey for colonies that consumed more winter stores than the average from October to April.

Cessation of brood rearing in August, September, and October resulted in corresponding reduction in production the following summer of 141, 106, and 60 lb (64, 48. 1, and 27. 2 kg) compared to colonies allowed to rear brood into late fall. A test conducted during two winters using cutaway hive bodies with exposed combs emphasized the importance of wind protection for winter survival.

Key words: honey bees, overwintering, combs, package bees, queens, beekeeping management, and brood-rearing.

Washington, D. C. February 1977

Floyd E. Moeller

Introduction

Honey bees, Apis mellifera L., are kept by man in bee hives, but bees are not domestic animals in any sense of the word. Man adapted his handling and management of these insects by fitting his methods to meet their natural behavior. Bees are no different in their needs or behavior today than were the wild honey bees in the forests at the time of the cave man. When bees swarm from modem hives, they readily return to their wild condition. They have been on earth since the Jurassic period, 160 million years ago, and have survived without man's help. The ideal conditions for winter survival in man's hives must thus approximate what is best in nature.

An analogy made by the late Dr. Farrar (5)1 2 stated that a honey bee colony is in reality an organism and that the colony lives from now on, unless the victim of disease, starvation, or catastrophe, whereas individual bees of the colony die or are replaced continuously, as are the cells of any living organism. Reproduction of this colony organism is by swarming.

1

Research entomologist, Bee Management and Entomology Research, Agricultural Research Service, Madison, Wis. 53706

2

Italic numbers in parentheses refer to Literature Cited, p. 14.

Honey bees were brought to the Americas by early European immigrants. The bees soon escaped from the settlements, went into the wilds of the new world, and lived in hollow trees and caves. When left to their own resources they are adaptable and have little trouble surviving severe winters. Only when man interferes do problems develop.

Bees build combs in many and varied cavities: hollow trees, between the studs in walls of buildings, attics, caves, or any suitable shelter. The main purpose in choosing such enclosures is to provide the colony with protection from winter winds. No attempt is made to heat or control the temperature of the chosen cavity.

Perhaps no other subject in beekeeping management has been discussed and argued as much as methods of overwintering honey bee colonies. Many northern beekeepers over the years have killed their colonies in the fall and depended on package bees for spring replacement. With higher honey prices, many southern package bee producers are turning to honey production. Intense interest is expressed by beekeepers in overwintering colonies of bees, largely because of the unavailability of package bees and queens and high prices.

The package bee colony, 2- or 3-lb (1- or 1.5-kg) size, requires about 11 to 12 weeks to reach maximum population (6). This is governed by the length of time required to develop a bee from the time the egg is laid to emergence (20 days), by the longevity of the bees (30 to 35 days), and by the amount of brood a given population can support (3, 7). A package of bees installed May 1 will consequently reach peak population about August 1. This means that if a major honey flow occurs June 15 to August 1, the colony is building its population on the flow and does not store a maximum crop.

A properly managed overwintered colony reaches its peak June 15 (at the start of the flow) and is capable of maximum production. For this reason, overwintered colonies are preferred. In areas where a maximum crop from an overwintered colony is 250 lb (113. 6 kg), the package colony may produce only 80 to 100 lb (36 to 46 kg).

Bees store pollen and honey during the active summer period. This cache of food stored in vertically hanging combs is slowly consumed during the winter. Brood rearing begins about the first of January, and the brood area expands as food and exterior temperatures permit. In the area occupied by brood, the temperature is maintained at about 92° to 93° F (33° C).

At the outer periphery of the roughly spherical cluster occupying the interspaces of the combs, the bees are tightly packed to form an insulating band or shell. The outer edge of this cluster never falls below 43° F (6. 11° C) (10) and is usually in the mid-50° (12-13°) range. If the body temperature of a bee falls to 42° (5. 56°), it loses the power of motion and will drop. At 28. 5° (1. 94°) the body tissue freezes solid. Thus, to maintain life the temperature cannot go below 43° (6. 11°).

In the remainder of the hive space not occupied by bees, the temperature falls just as low as the outside. Colonies that build combs in such exposed places as on limbs of trees cannot withstand the cold, piercing winds of northern climates and will not survive. Thus, the main purpose for seeking the confines of a cavity seems to be wind protection.