Bees

Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea and are presently considered a clade, called Anthophila. There are nearly 20,000 known species of bees in seven recognized biological families.^[1][2]They are found on every continent except Antarctica, in every habitat on the planet that contains insect-pollinated flowering plants.

Some species including honey bees, bumblebees, and stingless bees live socially in colonies. Bees are adapted for feeding on nectar and pollen, the former primarily as an energy source and the latter primarily for protein and other nutrients. Most pollen is used as food for larvae. Bee pollination is important both ecologically and commercially; the decline in wild bees has increased the value of pollination by commercially managed hives of honey bees.

Bees range in size from tiny stingless bee species whose workers are less than 2 millimetres (0.08 in) long, to Megachile pluto, the largest species of leafcutter bee, whose females can attain a length of 39 millimetres (1.54 in). The most common bees in the Northern Hemisphere are the Halictidae, or sweat bees, but they are small and often mistaken for wasps or flies. Vertebrate predators of bees include birds such as bee-eaters; insect predators include beewolves and dragonflies.

Human beekeeping or apiculture has been practised for millennia, since at least the times of Ancient Egypt and Ancient Greece. Apart from honey and pollination, honey bees produce beeswax, royal jelly and propolis. Bees have appeared in mythology and folklore, through all phases of art and literature, from ancient times to the present day, though primarily focused in the Northern Hemisphere, where beekeeping is far more common.

 The life cycle of a bee

it a solitary or social species, involves the laying of an egg, the development through several moults of a legless larva, a pupation stage during which the insect undergoes complete metamorphosis, followed by the emergence of a winged adult. Most solitary bees and bumble bees in temperate climates overwinter as adults or pupae and emerge in spring when increasing numbers of flowering plants come into bloom. The males usually emerge first and search for females with which to mate. The sex of a bee is determined by whether or not the egg is fertilised; after mating, a female stores the sperm, and determines which sex is required at the time each individual egg is laid, fertilised eggs producing female offspring and unfertilised eggs, males. Tropical bees may have several generations in a year and no diapause stage. 

The egg is generally oblong, slightly curved and tapering at one end. In the case of solitary bees, each one is laid in a cell with a supply of mixed pollen and nectar next to it. This may be rolled into a pellet or placed in a pile and is known as mass provisioning. In social species of bee there is progressive provisioning with the larva being fed regularly while it grows. The nest varies from a hole in the ground or in wood, in solitary bees, to a substantial structure with wax combs in bumblebees and honey bees.

The larvae are generally whitish grubs, roughly oval and bluntly-pointed at both ends. They have fifteen segments and spiracles in each segment for breathing. They have no legs but are able to move within the confines of the cell, helped by tubercles on their sides. They have short horns on the head, jaws for chewing their food and an appendage on either side of the mouth tipped with a bristle. There is a gland under the mouth that secretes a viscous liquid which solidifies into the silk they use to produce their cocoons. The pupa can be seen through the semi-transparent cocoon and over the course of a few days, the insect undergoes metamorphosis into the form of the adult bee. When ready to emerge, it splits its skin dorsally and climbs out of the exuviae as a winged adult and breaks out of the cell.