The giant bee is said to be the size of a human thumb and hasn't been seen since 1981 (illustrative picture).
Megachile pluto is the world's largest bee, which is approximately four times larger than a European honeybee.
It's been 38 years since scientists last spotted the rare species found only in a group of Indonesian islands. Describing it, he said it was a "large black wasp-like insect, with enormous jaws like a stag-beetle".
The bees build communal nests on termite dwellings, researcher Adam Messer observed in the 1980s. Since then, the species has been lost to science.
He explains on the website his incredible journey to find the bee alive, which started almost two decades ago when he first learned of Wallace and his travels.
Unfortunately for scientists and bee-lovers, not a single one of them has been seen since 1981.
The team's local guide pointed them in the direction of a termite nest in a tree and noticed something inside moving after shining his phone light into the perfectly round hole in the top.
"It was absolutely breathtaking to see this "flying bulldog" of an insect that we weren't sure existed anymore, to have real proof right there in front of us in the wild To actually see how handsome 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", Bolt said in a statement. They collaborated with Robson and Canadian-born writer Glen Chilton to track down the elusive monster bee-and they succeeded.
While the bee has once-again been found, it's hard to say how long it will stay. "The vast majority of the 20,000 known species of bee in the world are quite calm and not aggressive", he said.
"My goal was to be the first person to make a photo of a living Wallace's Giant Bee and I had achieved that goal", he added.
"Messer's rediscovery gave us some insight, but we still know next to nothing about this extraordinary insect", Wyman said, echoing the reaction of other experts after the bee was spotted anew.
In a blog post for the environmental group Global Wildlife Conservation, Clay Bolt said: "It was absolutely breathtaking to see this flying bulldog of an insect that we weren't sure existed anymore, to have real proof right there in front of us in the wild".
In addition to its Brobdingnagian size, Wallace's giant bee sports unusually large mandibles, which are often compared to a stag beetle's.