Internal anatomy of a bee

Internal anatomy of a bee
Internal anatomy of a bee: hive-dwelling social insect which produces honey and wax.
Dorsal aorta: blood vessel in the back of a bee that carries blood from the heart to the organs.
Esophagus: part of the digestive system just after the mouth.
Heart: blood-pumping organ.
Intestine: final part of the digestive system.
Rectum: last part of the intestine.
Sting: stinger of a bee.
Nail: pointed nail of a bee.
Venom sac: pocket containing the bee's venon.
Crop: bulge between the esophagus and the gizzard of a bee.
Ventral nervous system: the collection of nerves in the abdomen.
Pharynx: intersection of the respiratory and digestive tracts.
Antenna: organ of touch of a bee.
Brain: seat of the mental faculties of a bee.
Salivary gland: glandular organ that produces saliva.

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EN : Bumblebee
FR : Bourdon
ES : Abejorro


A bumblebee or bumble bee is any member of the bee genus Bombus, in the family Apidae; there are over 250 known species primarily occurring in the Northern Hemisphere.

Bumblebees are social insects that are characterized by black and yellow body hairs, often in bands. However, some species have orange or red on their bodies, or may be entirely black. Another obvious, but not unique, characteristic is the soft nature of the hair (long, branched setae), called pile, that covers their entire body, making them appear and feel fuzzy. They are best distinguished from similarly large, fuzzy bees by the form of the female hind leg, which is modified to form a corbicula; a shiny concave surface that is bare, but surrounded by a fringe of hairs used to transport pollen, in similar bees, the hind leg is completely hairy, and pollen grains are wedged into the hairs for transport.


Like their relatives the honey bees, bumblebees feed on nectar and gather pollen to feed their young.

The blood or hemolymph, as in other arthropods, is carried in an open circulatory system. The body organs, "heart" (dorsal aorta), muscles, etc. are surrounded in a reservoir of blood. The dorsal aorta does pulse blood through its long tube, though, so there is a circulation of sorts.

In fertilised queens the ovaries are activated and when the queen lays her egg it passes along the oviduct to the vagina. In the vagina there is a container called the spermatheca. This is where the queen stored sperm from her mating. Before she lays the egg she will decide whether to use sperm from the spermatheca to fertilise it or not. Non-fertilised eggs grow into males, and only fertilised eggs grow into females and queens.

As in all animals hormones play a big role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in the other female worker bees while the queen remains dominant. Salivary glands in the head secrete saliva which is mixed with the nectar and pollen. Saliva is also mixed into the nest materials to soften them. The fat body is a nutritional store; before hibernation queens eat as much as they can to enlarge their fat body, and the fat in the cells is used up during hibernation.

Like all bee tongues, the bumblebee tongue (the proboscis) is composed of many different mouthparts acting as a unit, specialised to suck up nectar via capillary action. At rest or when flying the proboscis is kept folded under the head. The abdomen is covered with dorsal tergites and ventral sternites. Wax is secreted from glands on the sternites.

The brightly-coloured pile of the bumble bee is a form of aposematic signal. Depending on the species and morph, these colours can range from entirely black, to bright yellow, red, orange, white, and pink. Thick pile can also act as insulation to keep the bee warm in cold weather. Further, when flying a bee builds up an electrostatic charge, and as flowers are usually well grounded, pollen is attracted to the bee's pile when it lands. When a pollen covered bee enters a flower, the charged pollen is preferentially attracted to the stigma because it is better grounded than the other parts of the flower.

A bumblebee does not have ears, and it is not known whether or how a bumblebee could hear sound waves passing through the air, however they can feel the vibrations of sounds through wood and other materials.

Bumblebees are typically found in higher latitudes and/or high altitudes, though exceptions exist (there are a few lowland tropical species). A few species (Bombus polaris and B. alpinus) range into very cold climates where other bees might not be found; B. polaris can be found in northern Ellesmere Island, the northernmost occurrence of any eusocial insect, along with its parasite, B. hyperboreus. One reason for this is that bumblebees can regulate their body temperature, via solar radiation, internal mechanisms of "shivering" and radiative cooling from the abdomen, called heterothermy. Other bees have similar physiology, but it has been best studied in bumblebees.

Bumblebees form colonies. These colonies are usually much less extensive than those of honey bees. This is due to a number of factors including: the small physical size of the nest cavity, the fact that a single female is responsible for the initial construction and reproduction that happens within the nest, and the restriction of the colony to a single season (in most species). Often, mature bumblebee nests will hold fewer than 50 individuals, and may be within tunnels in the ground made by other animals, or in tussock grass. Bumblebees sometimes construct a wax canopy ("involucrum") over top of their nest for protection and insulation. Bumblebees do not often preserve their nests through the winter, though some tropical species live in their nests for several years, and their colonies can grow quite large, depending on the size of the nest cavity. The last generation of summer includes a number of queens who overwinter separately in protected spots. The queens can live up to one year, possibly longer in tropical species.

Bumblebee nests are first constructed by over-wintered queens in the spring, in temperate areas. Upon emerging from hibernation, the queen collects pollen and nectar from flowers and searches for a suitable nest site. The characteristics of the nest site vary among bumble bee species, with some species preferring to nest in underground holes and others in tussock grass or directly on the ground. Once the queen has found a site, she prepares wax pots to store food and wax cells into which eggs are laid. These eggs then hatch into larvae, which cause the wax cells to expand isometrically into a clump of brood cells.

bumble bee

These larvae need to be fed both nectar for carbohydrates and pollen for protein in order to develop. Bumblebees feed larvae nectar by chewing a small hole in the brood cell into which nectar is regurgitated. Larvae are fed pollen in two ways, depending on the bumblebee species. So called "pocket-maker" bumblebees create pockets of pollen at the base of the brood cell clump from which the larvae can feed themselves. Conversely, "pollen-storer" store pollen in separate wax pots and feed it to the larva in the same fashion as nectar. Bumble bees are incapable of trophallaxis, direct transfer of food from one bee to another.

With proper care, the larvae progress through four instars, becoming successively larger with each molt. At the end of the fourth instar the larvae spin silk cocoons under the wax covering the brood cells, changing them into pupal cells. The larvae then undergo an intense period of cellular growth and differentiation and become pupae. These pupae then develop into adult bees, who chew their way out of the silk cocoon. When adult bumble bees first emerge from their cocoons, the hairs on their body are not yet fully pigmented and are a greyish-white colour. The bees are referred to as "callow" during this time, and they will not leave the colony for at least 24 hours. The entire process from egg to adult bee can take as long as five weeks, depending on the species and the environmental conditions.

After the emergence of the first or second group of workers, workers take over the task of foraging and the queen spends most of her time laying eggs and caring for larvae. The colony grows progressively larger and at some point will begin to produce males and new queens. The point at which this occurs varies among species and is heavily dependent on resource availability and environmental factors. Unlike the workers of more advanced social insects, bumble bee workers are not physically reproductively sterile and are able to lay haploid eggs that develop into viable male bumble bees. Only fertilized queens can lay diploid eggs that mature into workers and new queens.

Early in the colony cycle, the queen bumble bee compensates for potential reproductive competition from workers by suppressing their egg-laying by way of physical aggression and pheromonal signals. Thus, the queen will usually be the mother of all of the first males laid. Workers eventually begin to lay males later in the season when the queen's ability to suppress their reproduction diminishes. The reproductive competition between workers and the queen is one reason that bumble bees are considered "primitively eusocial".

New queens and males leave the colony after maturation. Males in particular are forcibly driven out by the workers. Away from the colony, the new queens and males live off nectar and pollen and spend the night on flowers or in holes. The queens are eventually mated, often more than once and search a for suitable location for diapause.

Bumblebees generally visit flowers exhibiting the bee pollination syndrome. 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 nectar and pollen continue to be available. While foraging, bumblebees can reach ground speeds of up to 15 m/s (54 km/h).

When bumblebees arrive 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 corbiculae "pollen baskets". 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 necta).

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. However, because bumblebees are much more opportunistic feeders than honey bees, these shortages may have less profound effects. Nectar is stored essentially in the form it was collected, rather than being processed into honey as is done in honey bees; it is therefore very dilute and watery, and is rarely consumed by human.

Bumblebees of the subgenus Psithyrus (known as cuckoo bumblebees, and formerly considered a separate genus) are a lineage which has lost the ability to collect pollen, and live parasitically in the colonies of other bumblebees. Before finding and invading a host colony, a Psithyrus female (there is no caste system in these species) will feed directly from flowers. Once she has infiltrated a host colony, the Psithyrus female will kill or subdue the queen of that colony and forcibly (using pheromones and/or physical attacks) "enslave" the workers of that colony to feed her and her young. The female Psithyrus also has a number of morphological adaptations, such as larger mandibles and a larger venom sac that increase her chances of taking over a nest. Upon hatching, the male and female Psithyrus disperse and mate. Like non-parasitic bumblebee queens, female Psithyrus find suitable locations to spend the winter and enter diapause upon being mated.

Xylocopa tabaniformis  Carpenter bee  Abeille charpentière  Abeja carpintera

Carpenter bee

Carpenter bees are large, hairy bees distributed worldwide. There are some 500 species of carpenter bee. Their name comes from the fact that nearly all species except those in the subgenus Proxylocopa, which nest in the ground, build their nests in burrows in dead wood, bamboo, or structural timbers. Members of the related tribe Ceratinini are sometimes referred to as "Small Carpenter Bees". A few species bore holes in wood dwellings and earn the enmity of some homeowners, though others regard them as pets.

In several species, the females live in tunnels alongside their own daughters or sisters, creating a sort of social group. They use wood bits to form partitions between the cells in the nest. A few species bore holes in wood dwellings. Since the tunnels are near the surface, structural damage is generally minor or nonexistent. Carpenter bees can be important pollinators on open-faced flower, even obligate pollinators on some, such as the Maypop (Passiflora incarnata), though many species are also known to "rob" nectar by slitting the sides of flowers with deep corollas. In the United States, there are two eastern species, Xylocopa virginica, and Xylocopa micans, and three other species that are primarily western in distribution, one being Xylocopa varipuncta. X. virginica is by far the more widely distributed species.

Some are often mistaken for a bumblebee species, as they can be similar in size and coloration, though most carpenter bees have a shiny abdomen, while in bumblebees the abdomen is completely clothed with dense hair. Males of some species have a white or yellow face, where the females do not; males also often have much larger eyes than the females, which relates to their mating behavior. Male bees are often seen hovering near nests, and will approach nearby animals. However, males are harmless since they do not have a stinger. Female bees do have a stinger, but are not aggressive, and will not sting unless directly provoked.

Animation : Bumblebee