The rare insect has now been photographed and filmed alive for the first time on the North Maluku islands of Indonesia, which will hopefully increase our understanding of its species.

On a small island in northern Indonesia, a team of researchers have found the world's largest species of bee. Wallace's giant bee (Megachile pluto), which can reach four times the size of a honeybee, was last seen alive by scientists in 1981. But last year, researchers found one specimen in a Dutch museum that was collected in 1991, while two more fresh individuals went up for auction and were sold to private collectors. Proving that the bees were clearly still alive, these events also revealed a worrying trade in specimens. This January, a team made up of researchers from Princeton University, the University of Sydney, Central Queensland University, Saint Mary's University in Canada and local guides set out to locate the insect. After five days of searching the rainforest on a small Indonesian island and staring at termite mounds in trees, the day before the team were due to leave they finally spotted what they had only hoped of finding: Wallace's giant bee.

Clay Bolt, the wildlife photographer who took the images and video of the insects, says, 'To actually see how beautiful and big the species is in life, to hear the sound of its giant wings thrumming as it flew past my head, was just incredible. 'It was absolutely breathtaking to see this "flying bulldog" of an insect, to have real proof right there in front of us of it in the wild.' The world's largest species of bee The intrepid naturalist Alfred Russel Wallace is the first known to have collected the species in 1859, when he was exploring Bacan Island, part of the North Maluku islands of northern Indonesia. It was during these travels through the Malay Archipelago that he first formed the theory of evolution. He managed to collect just one female bee, describing it as 'a large black wasp-like insect, with immense jaws like a stag-beetle'. At the time it was not known why the females had such a particularly large set of mandibles. This mystery would be solved over a hundred years later. Despite the insect's size and position as the world's largest bee, decades went past without another sighting of what became known as Wallace's giant bee.

That was until, in 1981, the American entomologist Adam Messer saw the bee on Halmahera island, not far from the original location where Wallace first found the insect. Further surveys revealed that not only was it still present on Bacan Island, but that it was also living on the much smaller island of Tidore. Messer was able to make the first-ever behavioural observations of Wallace's giant bee, finally revealing why the females had such distinctive mandibles. He found that the bees would build nests in the mounds of tree-dwelling termites belonging to Microcerotermes amboinensis. To make tunnels and chambers, the bees would use their large mandibles collect and carry resin from other trees. This resin was then used to line the inside of the bee's nest before it hardened, to prevent termites from entering. The females were found to be much larger than the males, which also lacked the large mandibles. The males were instead observed practicing territorial behaviour near the nests, which contained as many as six individual females and 22 developing larvae. During these surveys, Messer noted that not every termite mound contained bees, suggesting that the insects naturally occur in low numbers. This provides at least one explanation for why they flew under the radar for so long. After these observations, however, Wallace's giant bee was lost once more.

Prized by collectors It is not that unusual for an insect such as Wallace's giant bee to go 'missing' for such a stretch of time. Its local rarity, the fact that it was only known from a smattering of small Indonesian islands and the general lack of research into these animal groups are all factors that mean it is quite easy for insect species to drop off the radar. But at the beginning of 2018 there were some ominous findings. Just as some entomologists were giving up hope for the species's survival in the face of such rapid development and deforestation across much of Indonesia, in March last year a single fresh female giant bee appeared on an online auction site. Collected on Bacan Island, the bee sold to a private collector for just under £7,000 ($9,100). Within less than a year, a second specimen appeared on the same website and this time sold for £3,200 ($4,150). Despite not having been recorded as seen for almost four decades, these sales are presumably considered legal by international standards as the species is not covered by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) - but that isn't the whole picture. Under national law, the bees were almost certainly illegal as the Indonesian government is very careful about specimens they allow to be exported. This makes appearance of the bee in auctions - and, more worryingly, the high prices they command - a serious cause for concern.