Bumble bees

A bumble bee belongs to the bee genus Bombus, and are known as social insects. This means that they live in a colony which is headed by a queen. Unlike honey bees which live in colonies often exceeding 50,000 bees, bumble bees live in colonies of just 50 or so.

In summer a colony may contain 50-200 workers (females), but only the large queen bumble bees survive the winter. In spring these queens emerge from hibernation and each searches for a warm, dry, undisturbed place in which to nest, perhaps underground or among vegetation at the surface. The queen supplies the nest with pollen and nectar, and lays her first batch of eggs. She keeps them warm and when they hatch she feeds and cares for the larvae until they develop into adult workers, which then help their mother to forage for pollen and nectar. The queen continues to lay more eggs. At first these develop into more worker bees and the colony grows larger. Eventually in June or July, males and new queens are produced instead of workers. The males and new queens leave the nest and mate. After mating, the new queens dig themselves into the soil in a cool place and hibernate. The old queen, workers and males die before winter sets in, leaving the old nest empty.

They can visit patches of flowers up to 1-2 kilometres from their colony. Bumblebees will also tend to visit the same patches of flowers every day, as long as they continue to find nectar and pollen, a habit known as pollinator or flower constancy. While foraging, bumblebees can reach ground speeds of up to 15 metres per second (54 km/h).

Experiments have shown that bumblebees use a combination of colour and spatial relationships to learn which flowers to forage from. Bumblebees can also detect both the presence and the pattern of electric fields on flowers, which occur due to the positive static charges that are generated when bees fly through the air (see Atmospheric electricity), and take a while to leak away into the ground. They use this information to find out if a flower has been recently visited by another bee. After arriving at a flower, they extract nectar using their long tongue ("glossa") and store it in their crop. Many species of bumblebee also exhibit what is known as "nectar robbing": instead of inserting the mouthparts into the flower normally, these bees bite directly through the base of the corolla to extract nectar, avoiding pollen transfer. These bees obtain pollen from other species of flowers that they "legitimately" visit.

Pollen is removed from flowers deliberately or incidentally by bumblebees. Incidental removal occurs when bumblebees come in contact with the anthers of a flower while collecting nectar. The bumblebee's body hairs receive a dusting of pollen from the anthers, which is then groomed into the corbicula ("pollen basket"). Bumblebees are also capable of buzz pollination.

In at least a few species, once a bumblebee has visited a flower, it leaves a scent mark on the flower. This scent mark deters visitation of the flower by other bumblebees until the scent degrades. It has been shown that this scent mark is a general chemical bouquet that bumblebees leave behind in different locations (e.g. nest, neutral, and food sites), and they learn to use this bouquet to identify both rewarding and unrewarding flowers. In addition, bumblebees rely on this chemical bouquet more when the flower has a high handling time (i.e. it takes a longer time for the bee to find the nectar).

Once they have collected nectar and pollen, bumblebees return to the nest and deposit the harvested nectar and pollen into brood cells, or into wax cells for storage. Unlike honey bees, bumblebees only store a few days' worth of food and so are much more vulnerable to food shortages

This type of bee species is non aggressive and will only sting when defending itself. Like all bees they are excellent pollinators and this is partly why there is so much concern for the decline in bumble bee populations. There are approximately 300 known species of bumble bee around the world and many of these are found in the northern hemisphere.

http://en.wikipedia.org/wiki/Bumblebee

http://www.nhm.ac.uk/research-curation/research/projects/bombus/