Bees other than honey bees
The best known of all the bees is the honey bee, as people have been harvesting their honey and wax for at least seven thousand years. However, there are thousands of bee species occurring worldwide. Different types of bees have different lifestyle strategies. They may be entirely solitary or entirely social, and between these two extremes is a whole range of intermediate forms. Most of these other bees are not utilised by people, other than the important benefit they gain from the bees' pollination services for crops and the environment. The stingless bees, have been (and still are in some areas) used by people in the tropics and sub-tropics for honey harvest, and have a rich cultural significance in these parts of the world.
All groups of bees are specialised hymenoptera insects evolving from the sphecoid wasps, the difference being that the protein portion of their diet is derived solely from pollen - unlike wasps which obtain some protein from animal sources. Consequently, the evolutionary history of bees is closely connected with that of flowering plants. Characteristics of all bees are the wide variety of nest types, typical egg, larva, pupa and adult metamorphic development, and the ability to navigate back to the nest.
At least 15,000 species of bee have been described with the vast majority of these bees being solitary. Solitary bees have no worker caste and construct and provision their nest without co-operating with others. They are highly seasonal, usually with one generation annually and timing their emergence to coincide with peak flowering in a given habitat. Their life cycle is emergence (sometimes from hibernation mating) nest site choice, nest construction followed by brood production - maybe 6-12 offspring. Production of young follows the cycle of constructing a single brood cell, provisioning the cell, egg laying and cell closure before moving on to the next egg laying cycle.
The next step in the development of sociality is the aggregation of nests of solitary bees. Hundreds or even thousands can live closely together in a given area (termed quasi-sociality) and sociality may arise (in evolutionary terms) from the sharing of single nest entrances - ultimately leading to two or more females sharing a nest and co-operating in the rearing of the young.
At its simplest, social behaviour can be considered as a single female remaining with the nest and cooperating with her offspring to raise further young. In semi social colonies, a group of females of the same age work together to rear young. Outwardly, they are identical but physiologically some females have enlarged ovaries and are able to lay eggs while others have diminished ovaries and forage for provisions instead. With increasing levels of eusociality, the cooperation between generations and siblings increases. This type of colony will be founded by a single mated female. As daughters are raised, a rough division of labour develops, giving the potential for better survival of all the colony inhabitants and there will be several daughter generations. Later, perhaps triggered by the contraction of food supplies, the composition of the colony changes. The old queen will begin to reach the end of her life span and will be replaced by a new one.