Wallace’s Giant Bee

Wallace's Giant Bee Classification
Class: Insecta
Order: Hymenoptera
Family: Megachilidae
Genus: Megachile (Callomegachile)
Species: M. pluto

Wallace’s giant bee is an Indonesian resin bee and the largest known living bee species. It has been thought twice that Wallace’s giant bees are extinct. It was not until 2019 that an expedition was undertaken on the islands of Indonesia following in the footsteps and journals of the original discoverers.

In addition to being affected by tropical, heat-related illnesses, these explorers spent several days in search of the elusive Megachile pluto without success. On the final day, they discovered Wallace’s giant bee.

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    What Is Wallace's Giant Bee?

    Wallace’s Giant Bee (Megachile pluto) is the largest bee species known in existence and is named after the person who discovered it. (Alfred Russell Wallace)

    The Wallace’s giant bee belongs to the cosmopolitan Megachile genus and is a solitary bee. The Wallace’s giant bee does not make large amounts of honey nor live in a social, queen-led colony like other species. Since solitary bees do not generally operate in the same way as the common honey bee hive colonies, this is to be expected.

    Among Wallace’s giant bee’s other names are the Indonesian resin bee, “Raja ofu” or “Rotu ofu” which means “king or queen of the bees, respectively.” Additionally, the 2019 expedition also gave rise to the nickname of the “flying bulldog.”[1] Some members of this family are referred to as mason bees or leafcutter bees.

    Is Wallace's Giant Bee Extinct?

    Despite not being extinct, Wallace’s giant bees are becoming increasingly rare as a consequence of the deforestation of their habitat. The Wallace’s giant bee continues to be threatened by local palm oil production, and if conservation measures are not taken seriously, it may become extinct in the future.

    Initially discovered in 1859 by Alfred Russell Wallace, the scientific world at large believed Wallace’s giant bee to be extinct until another discovery over a century later, in 1981, by Adam C. Messer.

    During this period, Adam C. Messer documented six Wallace’s giant bee nests on Bacan island and several other surrounding islands. Despite Wallace’s giant bees’ considerable size, there were no other recording sightings from 1981 to 2019.

    After an absence of 38 years, a group of biologists from all over the world took on the challenge of finding Wallace’s giant bees.

    As part of a five-day exhibition aimed at finding Wallace’s giant bee nests, several biologists and scientific professionals from the University of Sydney, Princeton, Central Queensland, and Saint Mary’s University in Canada were accompanied by Clay Bolt, a natural history photographer from Montana.

    They began their search for Wallace’s giant bees on the Indonesian island cluster known as North Moluccas. On the final day of the search, their local guide spotted a termite nest approximately eight feet above ground level. It was in this nest that a Wallace’s giant bee, a female, was found.

    It was the first time a Wallace’s giant bee had been seen and recorded with modern, digital technologies and the first time official photographs had been taken since the species was last contacted in the early 1980s. Clay Bolt, a natural history photographer, had the privilege and responsibility to capture first-ever images of Wallace’s giant bees for the whole world to see.[2]

    Where Can Wallace's Giant Bees Be Found in the World?

    Wallace’s giant bee is an exceptionally rare species and can only be found in the Indonesian island cluster known as North Moluccas. This climate provides a warm, tropical, or lowland forest environment that is home to the Wallace’s giant bee and the trees they nest in.

    Due to the high market value of Wallace’s giant bees, scientists chose not to disclose the exact island or location in order to protect the giant bees. 

    Typically, Wallace’s giant bees nest in former tree termite homes and are also found in trees that are believed to be near extinction due to local palm oil production and other factors.

    How Can Wallace's Giant Bees Be Identified?

    You can identify the Wallace’s giant as being (in Wallace’s own words) “about as long as an adult human’s thumb, and a large, black, wasp-like insect, with immense jaws like a stag-beetle,” making it easily distinguishable among its species.[3]

    With a body of 1.5 inches and a wingspan of approximately 2.5 inches, the female Wallace’s giant bee is considered the world’s largest known bee species. This is four times the size of the average European honeybee.

    Female Wallace’s giant bees have large, stag-beetle-like mandibles and are nearly twice the size of their male counterparts, who measure just under an inch. 

    According to the Indonesia rediscovery party, another distinctive characteristic of Wallace’s giant bees is the sound produced by their wings, described as a “deep, slow thrum that you could almost feel as well as hear”.

    Is Wallace's Giant Bee Legally Protected?

    Despite the Wallace’s giant bee’s rarity and collectible appeal, there are as yet no legal protections for the M. pluto, which means that its acquisition and sale are legal. In 2018, a specimen of the Wallace’s giant bee was sold on eBay for over $9,000. According to experts, trends such as this could attract unscrupulous collectors, further jeopardizing the future of Wallace’s giant bee.[4]

    Due to the degradation of their local habitat, the Wallace’s giant bee has been classified as “vulnerable” by the International Union for Conservation of Nature (or ICUN). Wallace’s giant bees may be able to survive in other habitats, however, insufficient research has been conducted.[5]

    Wallace’s giant bees are approximately the size of a human thumb with a wingspan of approximately 2.5 inches and a body of 1.5 inches, which makes them four times the size of the average European honeybee.

    Female Wallace’s giant bees are larger than males, who are approximately half an inch smaller.

    European honey bee (Apis mellifera) compared to Wallace’s giant bee (Megachile pluto). Here, you can see the ten times the size difference between these very different bee species.

    Where Do Wallace's Giant Bees Live?

    Messer discovered that Wallace’s giant bees nest inside the nests of a specific species of tree-dwelling termite. Wallace’s giant bees are believed to use this strategy as a preservation strategy to help keep their whereabouts hidden from predators and, by extension, unscrupulous collectors.

    Using their ferocious-looking mandibles, Wallace’s giant bee females fashion a hole (entry and exit) in the bottom and coat it with resin. This hole is what indicated to the 2019 expedition that they had found the elusive Wallace’s giant bee species.

    Messer discovered that female Wallace’s giant bees harvest resin from vertical trunk fissures of trees by loosening it with their mandibles. By using the elongated labrum, as if it were a bulldozer blade, the female Wallace’s giant bee forms a resin ball that measures approximately 10 millimeters in diameter and returns it to her nest.

    Wallace’s giant bee nests are usually located high up in the trees, eight to ten feet from the ground, making them difficult to reach. [6]

    Does Wallace's Giant Bee Sting?

    Wallace’s giant bees can sting only once and sacrifice their lives to do so. It is only the female Wallace’s giant bees that are able to sting, usually for defensive purposes, whereas the males are unable to sting at all.[7] 

    The Megachile genus consists of mainly solitary bees, which do not have a hive filled with honey to protect and are considered very docile.

    The Wallace’s giant bee was vulnerable during its re-discovery period, so the biologists present did not test out its stinger’s effectiveness, although their accounts of the event indicated they would have liked to compare its pain levels with that of other bees and wasps.

    It was reported that the captured female Wallace’s giant bee appeared completely relaxed and non-aggressive. [8]

    Does Wallace's Giant Bee Pollinate?

    Wallace’s giant bee provides essential pollination services in its habitat, as do most Megachile bees. Among the 20,000 species of bees on earth, solitary bees, such as Wallace’s giant bee, constitute 70 percent of the population, and are the primary pollinators.

    Wallace’s giant bees thrive and pollinate in a mixed lowland and hill tropical habitat below 5,000 feet in the islands of Indonesia. In addition to containing over 17,000 islands, this country is ideally situated in a transitional zone between some of Earth’s largest flora and fauna habitat areas.

    Over 40,000 species of flowering plants and more than 5,000 orchid species call this region home. Even the largest flower in the world, known as the monster flower, Rafflesia arnoldii, can be found here. The world’s largest flower and the world’s largest bee (Wallace’s giant bee) share the same regional habitat. [9]

    Does Wallace's Giant Bee Make Honey?

    Solitary bees like Wallace’s giant bees aren’t prolific honey producers. Wallace’s giant bees will only collect the nutrients (nectar and pollen) necessary for the care of their own brood.

    Since Wallace’s giant bees do not produce honey that can be harvested by humans, the pollination services provided by most solitary bee species have been overlooked for decades. Over time, there is hope that protection and preservation efforts will increase as a result of the discovery and understanding of these crucial pollinators.

    Is Wallace's Giant Bee Dangerous?

    Female Wallace’s giant bees have the ability to sting, making them potentially dangerous, but they would most likely only do so in a defensive manner since they do not possess a honey-filled hive to defend. Biologists in Indonesia also described the Wallace’s giant bee as shy and difficult to find.

    A territorial behavior was observed among the male Wallace’s giant bees by researchers and entomologists who rediscovered this species in 2019. The Wallace’s giant female bee that photographer Clay Bolt captured for photography and study while in Indonesia was reported to be calm and non-threatening.

    What Does Wallace's Giant Bee Eat?

    As with most bees, Wallace’s giant bees eat nectar and pollen from their habitat’s flowering plants.

    Wallace’s giant bees are not like European honey bees who hoard their honey, but rather a single bee or a few female bees feeding only their own brood. Wallace’s giant bees therefore do not collect disproportionate amounts of nectar or pollen.

    Wallace's Giant Bee Reproduction and Lifecycle

    It is difficult for biologists and entomologists to report accurately about the reproduction and lifecycle of Megachile pluto (Wallace’s giant bee), however, the rediscovery has given conservationists hope that future studies may provide valuable information about Wallace’s giant bee.

    Generally, and also in the case of Wallace’s giant bee, bees are female-dominated species, with males playing a menial or limited role.

    Wallace’s giant bee males are smaller in size, by nearly half an inch, and are incapable of stinging. Despite some territorial behavior observed in Indonesia, Wallace’s giant bees’ primary function is to propagate the species.


    [1] [2] [3] rewild [4] Smithsonianmag [5] iucn [6] JSTOR [7] lucidcentral [8] National Geographic [9] World Atlas

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