Bumble Bee

The common bumblebee is one of the most social species on Earth. They congregate in vast colonies of fellow workers.

Led by a queen, bumblebees are almost a model of order and discipline. They cooperate, raise the young together, and divide up labor. Each bee has a specific role to promote the overall health and survival of the colony. Not all bees are like this, for example the carpenter bee looks like a bumble bee, but is more of a solitary bee.

However, due to complex reasons, bumblebee numbers appear to be in decline throughout the world. This may have severe long-term effects on the rest of the Earth’s ecosystems.

Bumblebee Facts

• Bumblebees are covered in a layer of oil that makes them more resistant to water.

• The bumblebee’s wings can only function in the appropriate temperatures. If the bee cannot take off, then it may shiver for several minutes to raise its internal temperature.

• Bumblebees are capable of producing a waxy substance to build nests and protect the eggs.

• In order to communicate with the colony, bumblebees have a remarkable intellectual ability compared to many insects. They can convey basic information to fellow workers and even remember complex patterns.

Bumblebee Scientific Name

Bumblebee is the common name for an entire genus of organisms called Bombus. According to the Merriam-Webster dictionary, the term Bombus comes from a Latin word meaning booming, buzzing, or humming. It is closely related to the Greek word bombos.

The bumblebee belongs to the family of Apidae, which compromises all types of bee species. It is closely related to the genus Meliponin, or the stingless bee. Altogether, there are more than 250 known species within the genus of Bombus. Several extinct species are also recognized in the fossil record. The genus may have evolved some 25 to 40 million years ago.

Bumblebee Appearance

The bumblebee can be identified by its rather large, plump appearance, its rounded abdomen, and the hair spread all over its body. They sport black and yellow colors — and sometimes even orange or red — in specific bands or patterns. These bright colors serve as a warning to other animals of the potential danger of threatening the bee.

In most species of bumblebees, there is a pollen basket located on the hind legs. This basket area features bare skin surrounded by small hairs to transport pollen around. Because of this, they can carry around a significant amount of their body weight in pollen.

The bumblebee has four wings to achieve flight. All of them are relatively small compared to its total body size. This has led to a common misconception that the bumblebee should be physically incapable of flight. However, this is based on a faulty idea of bumblebee flight. Many people assume that bumblebee wings are fixed. Instead, the bees can actually swivel or sweep their wings like a helicopter, so they flap their wings back and forth, rather than up and down. This creates eddies of air to help them remain aloft. They beat their wings approximately 100 to 200 times every second. They can sometimes remove pollen from a flower just by the vibration of flapping their wings near it.

The typical bumblebee is somewhere around half an inch to an inch long, which is about the size of a dime. The bee’s weight is likewise minuscule. However, this is not uniformly true across the entire genus. The largest bee species in the world is Bombus dahibomii from Chile. It can reach up to 1.6 inches in length.

One of the bee’s most important characteristics is the long tongue-like proboscis that has adapted specifically to lap up nectar from a flower. The proboscis comes in a variety of different sizes, from short to long. Each species tends to be specialized for a specific flower (though bumblebees with a short proboscis can sometimes “steal” food from a longer flower by poking a hole near the place where the food is located). The bees may end up traveling more than a mile to find an appropriate source of foods.

Bumblebee Behavior

The bumblebee relies on its wits and senses to search for their favorable flowers, including color and the presence of electric fields. Bumblebees tend to return to the same area to find food, but not necessarily the same flower. Once a flower is depleted, the bees will move on to a new one. They leave behind scent marks to tell fellow workers which flowers are bereft of nectar. The bumblebee is an integral part of the natural ecosystem, transporting pollen between male and female flower parts. Berries, tomatoes, and squash in particular are highly dependent on bumblebee pollination.

Studies have revealed that bumblebees may be more intelligent than first suspected. Upon finding a new source of food, they can communicate the location to fellow members of the colony. Consequently, bumblebees are highly social creatures that rely on the work of the entire colony to survive. A single colony usually contains up to 500 individuals at a time and occasionally even exceeds more than a thousand individuals. Although this may sound like a lot, it actually falls well short of the maximum number of honeybees in a colony.

At the center of the colony is a single dominant queen (though some species may have multiple). She is simultaneously the founder, leader, and matriarch of the colony. Each year around spring she establishes a hive at a suitable location close to a source of bumblebee foods. She builds the colony almost completely from scratch and produces most of the offspring herself. It is at her beck and call that the workers serve. This type of arrangement, which divides up workers into different castes, is known as eusocial behavior. It is fairly common in insects.

Both the queen and the female workers have a sharp stinger to defend against threats and predators. These stingers do not detach after use, so a bumblebee can strike a target repeatedly without injuring itself. Bumblebees will usually not bother people during their normal daily routine, but they can be quite aggressive about defending their colony. This may be a problem if the colony resides in a heavy population area.

Although most species of Bombus adhere to this basic eusocial behavior, the cuckoo bumblebee has a unique lifestyle altogether. As the name implies, it is a kind brood parasite that relies on other species to raise its young. The cuckoo bees will infiltrate another colony, kill the leader, and replace it with their own female in order to force the workers to feed their larvae. In this way, it is essentially hijacking the work of another bumblebee species.

Bumblebee Habitat

The bumblebee has an extensive range across North America, South America, Europe, Asia (minus parts of India and the Middle East), and Northern Africa. However, they are almost completely absent from Australia, sub-Saharan Africa, and Antarctica. The bumblebees can span all types of climates and geographical regions, including the tropics, but most species prefer temperate climates in high-altitude ranges.

Bumblebees will build nests somewhere close to the ground or below the ground. They can appropriate all kinds of environments into a suitable nest, including human buildings, abandoned animal nests, and even old furniture. The nest must be relatively cool and receive little direct sunlight.

Bumblebee Diet

Bumblebees have a rather simple diet of nectar and pollen, which they gather from flowers. They do not make honey in a traditional sense. Honey is produced from the long-term storage of nectar, and the bumblebees do not survive over the winter. However, they are capable of storing their food in small quantities for a few days at a time in the wax-like cells of the colony. For this reason, bumblebees are sometimes used by humans as pollinators, but not honey producers as many think.

Bumblebee Predators and Threats

Due to their relatively small size, bumblebees are prone to predation from a number of animals. Birds, spiders, wasps, and flies will prey on individual bumblebees when they are out foraging, while large predators like the badger can dig up and consume an entire colony in a matter of moments.

The stinger can be a formidable defense for the bee, especially when they are present in large numbers. This has enabled them to thrive for millions of years. However, bumblebees also face significant long-term problems from human activity and climate change.

Bumblebee Reproduction, Babies, and Lifespan

The bumblebee has a complex annual reproduction and life cycle that revolves around the health of the colony. The annual cycle begins in the winter, when the queen starts to build up enough fat to hibernate for the colder months. Upon emerging in the spring, she will then proceed to start a new colony and produce her first yearly offspring from the larvae.

The matriarch will produce a cluster of several eggs at one time. She fertilizes each egg individually from sperm stored in the spermatheca. She also has the ability to choose exactly which eggs to fertilize based on the needs of the colony. The fertilized eggs can become either regular females or more queens. The unfertilized eggs will become males, which go out into the world and attempt to mate. The matriarch will try to suppress the reproductive abilities of the females, so she will have exclusive reproductive rights with the males.

A typical bumblebee egg hatches into a larva after about two weeks of careful attention. The initial larva goes through several stages in its development. Each stage is known as an instar. When they are a week old, the larvae will produce cocoons for themselves so they can develop into mature adults. This cocoon stage is known as a pupa.

If successful, the colony will thrive throughout much of the summer months. The matriarch will continue to create new eggs, while the worker bees feed and take care of the subsequent offspring. During the fall, however, most of the existing colony dies off from natural causes. Since they do not survive the winter, bumblebees tend to have very short life cycles. Most of them live only for a month or two.

Bumblebee Population

Since the late 20th century, scientists have noted a curious and alarming phenomenon: bumblebee populations appear to be in precipitous decline throughout the world. Although exact population figures are hard to come by, it’s been estimated that bumblebee numbers have dropped by as much as 50 percent in some regions of the world.

Some species are in worse shape than others. For example, the variable cuckoo bumblebee and the rusty patched bumblebee are considered to be critically endangered by the International Union for the Conservation of Nature (IUCN)'s Red List. However, most are still vulnerable or least concern.

It is not entirely clear why numbers have dropped off. Pesticide use, habitat loss, and diseases have all been cited as potential causes. However, climate change may be greatly amplifying these underlying issues. One study noted that the largest declines in bumblebee populations occurred in the regions with the biggest changes in the climate. Besides addressing climate change, the elimination of pesticides and restoration of habitat might partially arrest the bumblebee’s decline.

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Sources:
1. David Burnie, Dorling Kindersley (2011) Animal, The Definitive Visual Guide To The World's Wildlife
2. Tom Jackson, Lorenz Books (2007) The World Encyclopedia Of Animals
3. David Burnie, Kingfisher (2011) The Kingfisher Animal Encyclopedia
4. Richard Mackay, University of California Press (2009) The Atlas Of Endangered Species
5. David Burnie, Dorling Kindersley (2008) Illustrated Encyclopedia Of Animals
6. Dorling Kindersley (2006) Dorling Kindersley Encyclopedia Of Animals