. WORKER BEES

WORKER BEES ARE IMPERFECT FEMALES maternally developed to provide all life support systems. Together with the sexually developed queen, also an imperfect female, the workers form the perfect female system- reproduction plus sustenance.

Worker honey bees are produced from fertilized eggs in 21 days (compared with 16 for queens). They lack fully developed sex organs as a result of a controlled diet that leads to hormonal deficiencies. However, some workers may develop functional ovaries and lay significant numbers of unfertilized eggs that develop into drones. Moreover, it is reported that worker bees in queenless colonies can produce female offspring from diploid eggs via parthenogenesis (that is, without mating). This occurs most frequently in one race of bees, which occasionally requeen colonies with worker-produced progeny.

Workers are the labor force of the colony, performing specialized duties based primarily on their age. Early in adult life they engage in hive duties such as brood rearing, comb construction, and colony defense, while late in their lives they become foragers.

Contrary to popular opinion worker bees are frequently idle, and foraging bees are highly opportunistic. Hive bees spend most of their time unproductively, and foragers prefer the most lucrative nectar and pollen sources. Although the divisions of labor are fairly clear-cut based on age, research has shown that in a worker population with an unbalanced age structure resulting from some catastrophic event, individual worker bees will adapt and assume duties that are not normal for their age. It has been shown that when bees are forced to modify their behavior in this fashion they perform less effectively than when they follow a normal sequence of development. Although the pheromones produced by the queen are necessary to maintain the integrity of the hive, worker bees are thought to control the fate of the colony by their activities, such as governing where and how many eggs the queen lays, replacing a failing queen, or ensuring the production of drones. The life span of worker bees is 4 to 6 months in the winter but only 28 to 35 days in the spring and summer.


Individual foraging bees readily discriminate between sources and normally retain a high degree of fidelity to a single source. Differences in foraging cues such as color, aroma, and taste are often subtle, but these modalities are handled with ease by the workers' sets of finely tuned receptor cells. Bees have an excellent sense of direction and time. Their chronometric powers permit them to emerge from the hive each day at the precise time a certain plant species begins to produce nectar or pollen. They also have an excellent memory, especially for odors. After one experience they can remember for 6 days; after three experiences they can remember for 2 weeks.

Honey bees forage between about 16'C (61'F) and 43'C (100'F). Honey bees are photonegative below 16'C; most plants do not even secrete nectar below 15.5'C (60'F). The honey bee eye, like that of many insects, is adapted to perceive rapid movement. This exceptional visual resolution enables bees in flight to discern the complex shapes and broken patterns of objects below, such as colored flowers against a green background. Bees have three visual pigments in each eye that permit them to see hues in the ultraviolet spectrum as well as the portion of the color spectrum (except red) visible to humans.

A bee collecting nectar normally makes 7 to 13 trips per day (the average is 10, the maximum recorded is 24), spending 27 to 45 min per trip. Flight speeds average 14.8 km (9.2 mi) per hour loaded and 13 km (8.1 mi) per hour empty. In doing so, a worker can visit as few as 5 or as many as 800 flowers in a single trip. When filled, the honey stomach can hold up to 85 percent of the weight of the bee. Bees collecting pollen usually take 6 to 10 minutes to gather a load, making 6 to 12 trips per day (the average is 10, the maximum reported is 47). On a single trip a bee will visit I to 200 flowers. The weight of a pollen load can be 20 to 33 percent of the weight of the bee. These estimates are variable, of course, and depend on the productivity of the plant source(s) involved and the needs of the colony. Research has shown that individual worker bees have an 804-km (500-mi) maximum lifetime flight limitation, determined by the exhaustion of her enzymatic mechanisms of carbohydrate metabolism.


When gathering pollen, a bee often uses both mouthparts and forelegs to dislodge pollen from the flower so that she becomes dusted with pollen. She then uses tarsal brushes on the foreleg to clean her mouthparts and head. Following this she uses similar brushes on her middle legs to clean the forelegs and thorax. Then with her hind legs she cleans the wings, abdomen, and middle legs. When cleaning the middle legs the bee grasps each leg between the pollen combs of the hind legs, drawing it past the combs. Interestingly, the result is that pollen taken from the right side of the bee is deposited in the left comb and vice versa. Then to pack the pollen the bee uses the rastellum (rake) on the opposite leg to clean each comb and force the pollen into the pollen press of that leg, which squeezes it (like toothpaste from a tube) up into the pollen basket on the outside of the hind leg. Thus in the packing process, pollen is moved from one side of the body to the other and then back again.

Since the tip of her sting is heavily barbed, the worker bee normally loses her sting when she impales an enemy as she attacks in self-defense or in defense of the hive. Shortly thereafter she dies as a result of a sizable loss of internal organs and tissue. If she doesn't lose her sting but empties the venom sac the worker is unable to replenish the venom. Adult worker bees must eat pollen (bee bread), grow, and mature before they have a full complement of venom. Venom gradually accumulates until the bees are about 15 days old. Hence, young bees are unable to sting effectively.


Some enemies of honey bees, such as skunks, are unaffected by large numbers of stings. Others, such as humans, may develop a hypersensitivity to the venom, which can be lethal; such people number less than 1 or 2 percent of the world population. (Recent studies have shown that most hypersensitive people do not react more intensively with each successive sting. Rather their level of reaction remains the same or decreases slightly with each event.) Normally, people who work with bees and are stung routinely eventually develop immunity to the extent that each additional sting produces only a small wheal or minimal swelling at the site of the sting.

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