Beekeeping in Northern climates
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Honey bees are social insects that live together in large numbers forming a colony. The colony consists of a single queen, many thousands of workers, a few to several hundred drones, and the immature stages that are referred to as brood. The colony constructs a wax nest consisting of several vertical "honey combs" used for both the rearing of brood as well as the storage of pollen and honey. In the center of the nest where the brood is reared is an area called the brood nest. Here the adult bees maintain a temperature between 90-95°F. Pollen and honey are stored around the brood nest. In nature, colonies are usually found living in darkened cavities, but they will readily accept our wooden "hives" as a home.
A very advanced degree of social behavior is exhibited by honey bees because there is both a distinct "caste system" between queens and workers, as well as a "division of labor" within the worker caste. There are two complementary female castes: the queen that provides all the egg laying activity and the workers that perform all the work associated with colony maintenance. Both the queen and workers are reared from fertilized eggs. The males, called drones, are reared from unfertilized eggs because of a phenomenon known as parthenogenesis. Caste determination in the two female castes is not genetic since a queen or worker can be reared from any egg or young developing larva. Rather, differential feeding of a larva with its subsequent effect on hormone production is what determines female caste.
DEVELOPMENT. The developmental states of the queen are shorter than those of the worker or drone, taking approximately 16 days from the time an egg is laid until an adult queen emerges. The approximate developmental time of each stage for the three castes is shown in the following table.
|Egg hatches after||3||3||3|
|Cell capped after||8||8||10|
|Adults emergy after||16||21||24|
The adult queen is easily identified since she is longer than the worker or drone and her abdomen extends well beyond her wings. She is a reproductively perfect female with welldeveloped ovaries and a sperm storage organ called the spermatheca. A virgin queen will normally mate with up to ten drones on one or two mating flights that are usually taken within seven days of her emergence from the queen cell. Mating occurs in the air and at a considerable distance from the colony. After mating, the queen returns and remains with her colony, functioning chiefly as an egg laying machine until her death. She does not mate again. A good queen in Minnesota will lay as many as 200,000 fertilized eggs per year. This tremendous egg production is made possible by the high protein diet of glandular secretion, royal jelly, that is provided to the queen by her worker attendants. The normal egg laying cycle in Minnesota begins in early January, increases through late June, and then gradually decreases until egg laying ceases in early October.
Queens will be reared by workers under three impulses:
- Swarming is usually a sign of hive congestion and in nature is the mechanism by which a colony reproduces.
- Supersedure occurs when the queen is failing (depleted spermatheca), damaged, or diseased.
- Emergency queen rearing occurs when the queen is suddenly removed or is killed.
In every case, queen rearing represents a management problem that must be corrected by the beekeeper.
QUEEN SUBSTANCE is a pheromone that is produced by the queen's mandibular glands. A pheromone is a chemical substance given off by one insect that causes a specific response by another individual of the same species. Queen substance inhibits queen cell building as well as regulating other behaviors. As long as a queen produces adequate amounts of queen substance the workers will not rear queens. When a queen is failing, the workers will construct supersedure cells. If the queen is killed by the beekeeper, the workers will modify normal worker cells to form emergency queen cells. When a colony makes preparations to swarm, the workers build special queen cells along the lower comb edges that are commonly called swarm cells.
One of the beekeeper's principal objectives is to prevent the colony from initiating supersedure or emergency queen cells, or allowing virgin queens to emerge from swarm cells. Queens can live for several years but the beekeeper should replace every queen with a new one every year, or at least every other year (depending on the management system).
The developmental stage of the worker honey bee lasts about 21 days or 30 % longer than that of the queen's developmental period. The adult worker is reproductively imperfect, with rudimentary ovaries and no spermatheca. Under normal conditions she cannot lay eggs. Although she is the smallest bee of the colony, the worker honey bee possesses many specialized structural features that allow her to perform a multitude of tasks essential to the continued existence of the colony. One such task of crucial importance to beekeepers is the ability to collect an excess of nectar and to regulate temperature, allowing the colony to be a perennial entity. Probably the most important task relating to the honey bees value to mankind, however, is the collection of plant pollen and nectar. This activity provides the pollination that is so fundamental to modern agriculture (see Appendix D).
LIFE SPAN AND DIVISION OF LABOR. The life span of an individual worker varies from season to season. Studies have shown that the life expectancy of adult worker honey bees emerging in early spring averages about 35 days, in early summer 25 days, but in early fall as long as 200 days. Under normal conditions, a worker performs a sequence of tasks during her life span starting with various in-hive activities like cell cleaning and larvae feeding. Eventually she will perform such activities as comb construction and nectar ripening. Well over half of her life is spent inside the hive and during this period she is generally referred to as a hive bee. Later, she progresses to foraging for nectar and pollen and is called a field bee. All workers in a colony, however, are capable of performing all worker tasks and can respond appropriately as conditions warrant. Foraging is probably the most hazardous occupation and is most detrimental to life span. During the summer season there are usually 45,000 to 55,000 adult worker honey bees in a strong, healthy colony.
Figure 2. Workers attending a marked queen.
The drone has the longest developmental period. He is slightly larger and more stout than the adult worker and has compound eyes so large they almost join on top of the head. Drones lack all of the specialized structures of workers and therefore make no direct contribution to the colony's existence. His importance cannot be discounted however. A drone's single function in life is to seek and mate with a virgin queen, a feat seldom accomplished. Mating, when effected, results in his death.
Most colonies begin to rear drones during mid-spring in cells that are larger than those used for rearing workers. It is normal for a colony to rear several thousand drones during the summer season and seeing several hundred drones in a large healthy colony should not be cause for concern. An overabundance of drones may indicate one or more of the following problems: 1) a disproportionate amount of drone comb; 2) a queen lacking sperm, or an adequate supply of sperm; 3) laying workers. In late summer all drones are driven from the hive by the workers and the drone brood removed. If a beekeeper observes an abundance of drones in the fall or winter, the colony probably has a failing queen.
Figure 3. Drones and workers. All workers in this photo have their heads in cells
The honey bee colony is truly an excellent example of the whole being greater than the sum of its parts. Individually, a bee can live for only a short time because it cannot carry out all the functions necessary for life. However, when that individual becomes part of a colony, it contributes some small part to the overall existence of the colony. It is through the total contribution made by the thousands of bees in a colony that ensures honey bees will live and prosper in the future world of insects.
See the related program: Honey Bees in Northern Climates