BEES (Part 2 of 3)   Leave a comment

Nesting and Life Cycle

Social insects, those living in communities and having differentiated forms or castes, as queens, workers, drones.

Bees vary greatly in nesting practices, depending upon the species. They may be classified as social bees, solitary bees, and parasitic bees (also called guest bees or cuckoo bees).

Social bees are members of colonies in which they cooperate with others to build the nest and to feed and protect the young. Colonies may contain as few as ten or as many as 80,000 bees. There are two kinds of females among the social bees, and they look quite different. The sexually mature, fertile females, called queens, are long and slender; the sexually undeveloped females, called workers, are small and chunky. The workers become their mother-queen’s helpers as housekeepers, nurses of the young, builders, guards to keep intruders from the nest, and foragers for food.

Only about 500 species of the more than 20,000 species of bees are social. They include honeybees, bumblebees, and tropical sting less bees.

Solitary bees care only for themselves and their immediate brood. Each female makes her own nest and cares for her offspring. The vast majority of bees are solitary, including leaf cutter bees, mining bees, and carpenter bees.

Parasitic bees, or guest bees, have no body parts for collecting pollen and do not feed or care for their offspring. They sneak into the nests of related species of bees to lay their eggs. The larvae that develop from these eggs are not welcome guests, because they often have huge jaws and use them to kill the larvae of their hosts. Parasitic bees are sometimes called cuckoo bees because, like the European cuckoo, which is a bird, they lay their eggs in the nests of others. Many species of sweat bees are parasitic.

During its life each bee undergoes a complete metamorphosis in four stages: egg, larva, pupa, and adult. The average bee egg is a tiny white sausage-shaped object about 14/100 inch (3.5 millimetres) long. From it hatches the larva, a white worm like grub with no eyes and no legs. After spending two or three weeks eating in its cell, the grub becomes less active as it enters the pupal stage. In some species the grub first spins a cocoon around itself before becoming a pupa. While outwardly still, inwardly the pupa is transforming into the adult bee.

The sex of the bee in most species is determined by whether or not the egg is fertilized. Fertilized eggs develop into females, infertilized ones into males. Male bees are called drones. They do no work and exist only for the possibility of mating with the females.

Honeybees

For at least 4,000 years honeybees have been kept for their honey and for beeswax, a tallow-like substance used to make candles, polishes, ointments, and many other products. Of great economic importance in most parts of the world, honeybees are native to Europe, western Asia, and Africa. They are also widespread in North America, where they were brought by the early white settlers.

The honeybees have a definite caste system; they are divided into three groups within the hive the queen, the workers, and the drones. The task of the queen is to lay eggs. The drones are males that can mate with the queen. The workers are female bees that do not lay eggs but do all the work necessary for the upkeep and protection of the hive.

Although bee keeping (also called apiculture) has been practised for many centuries, bees are not truly domesticated in the sense of being tamed. Those living in man-made hives behave no differently from those living in nests they make themselves.

In the wild, worker bees seek out a sheltered place such as a hollow tree or log, a cave, or a crevice in a rock or a building. Or they may choose to hang their nest from a tree branch. Using wax secreted between scale like plates on the underside of their abdomens, they build clusters of cells called combs. In the wild, combs may be somewhat rough and irregular, but each cell of the comb is a precisely shaped, six-sided tube open on one end. Two blocks of cells are placed back to back, forming a two-sided, or double-edged, comb. The comb hangs vertically with the open ends of the cells facing out the sides. To keep the larvae, which develop within, from falling out, cells are constructed with a slight upward tilt.

Bee keepers provide their colonies of bees with wooden boxes that are called hives. Inside the hives the bee keepers hang sheets of wax in wooden frames for the bees to use as foundations in building their combs. Ten or twelve of these frames can be hung side by side in each hive box.

As is the case in all colonies of social bees, the only sexually mature female honeybee is the queen. When she flies away from the nest to mate, she gives off an odour (a pheromone) that the drones find irresistible, and they follow her. The streamlined queen flies faster and higher than the majority of the short, stocky drones. As she soars upward, many of them give up the pursuit. From the few drones that can follow her as she continues on a rising, whirling flight, she chooses one to couple with. After mere seconds her mate falls dying to the ground, and she chooses another. Several drones in succession may meet the same fate before the queen returns to the nest alone. She never leaves the nest again, unless she moves with a swarm of worker bees to a new home. Fertile until shortly before she dies, she lays up to 2,000 eggs per day, one to a cell. The cells in which future workers and drones develop are similar and ordinary. But for the egg and larvae that will develop into a new queen, the cell must be enlarged. It usually resembles a peanut shell hanging from the comb.

Three days after it is laid, an egg hatches into a tiny larva. At first all larvae are fed royal jelly, or bee milk, a thick whitish nutritional substance that young worker bees regurgitate into the cells from a pair of glands. But only the future queens are kept on this diet. Future workers and drones are switched to beebread, made from pollen.

In about six days a larva grows to the size of an adult bee, filling its cell. Then a worker caps the cell with wax, and the larva inside spins a silk cocoon and becomes a pupa. In about 12 days the process of changing into a winged adult is at last completed, and the new bee emerges.

Newly emerged workers usually stay in the nest or hive for a time, first helping to clean out used cells, and then, when their glands begin producing royal jelly, feeding the larvae. At 10 to 16 days old the workers can secrete wax, which is softened by chewing and used to repair and construct cells.

Once the young worker’s wax glands stop producing, its job is to receive the nectar and pollen brought into the nest by older workers and to store it in the cells. By the age of 20 days the young worker may become a guard at the entrance to the nest. Eventually it leaves the nest to begin its lifelong career of foraging for nectar, pollen, water, or propolis. Propolis, also called bee glue, is a sticky resin from the buds of trees; it is used to repair cracks in the nest or hive and to cover the bodies of such intruders as moths, mice, or lizards that have been stung to death.

The division of work assignments in a hive is not rigid. Older bees may spend time at the nest or in the hive, eating and resting. They can reactivate their appropriate glands if young bees are few and the needs of the hive require more workers inside. A worker may live several months, but when there are empty cells and much nectar to be gathered she may work very hard and die in only six weeks.

Clustering and swarming. In the autumn the workers usually drive the drones away to starve or freeze. When winter arrives in cooler regions, all members of the honeybee colonies that nest in the open will die. But hive bees and those that nest in a sheltered spot can live through the cold weather by clustering. The bees of the colony huddle close together and form a ball around one of the combs. By moving their legs, wings, and bodies, the bees on the inside of the ball manage to keep warm, protected by the bees on the outside. And when the bees on the outside become cold, they change places with some of the bees on the inside. In extremely cold weather temperatures inside a cluster may be as much as 100° F (55° C) higher than outdoors. The cluster moves slowly as a unit over the combs so that the bees can eat the honey they have stored. Once midwinter is passed, the queen begins laying her eggs inside the cluster, starting a fresh colony.

When an old nest becomes crowded or a new queen emerges, honeybees may start a new colony by swarming. The old queen leaves the nest with a swarm of half the workers. Forming a dense throng around the queen, the swarm may hover in a tree while a few scouting workers seek out a suitable location for their new nest. If no new queen has emerged at the old nest, the workers remaining there rear larvae to be new queens, and the first one to emerge as an adult kills the others in their cells with her sting. The new queen quickly mates and begins laying eggs in 12 days.

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Posted 2012/02/15 by Stelios in Education

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