Lazarus effect: Wallace’s giant bee, thought extinct, rediscovered

When a species thought to be extinct reappears, this is known as the Lazarus effect. That is exactly what happened with Wallace’s giant bee (Megachile pluto)—in fact, twice already: after the species was rediscovered for the first time in 1981, a research team has now rediscovered the thumb-sized insect on the Indonesian Moluccas after it had not been recorded again since then.

Wallace’s giant bee is named after its discoverer, the British naturalist Alfred Russel Wallace, who found a female specimen in 1859 on Bacan Island in the Moluccas. Because no other specimen appeared for a long time, it was already assumed back then that the species had become extinct.

In 1981, however, the U.S. biologist Adam Messer succeeded in tracking down the species again: he found six bee nests on the Bacan islands of Bacan, Halmahera and Tidore. After that, there were no sightings for many years, so it was once more assumed that Wallace’s giant bee was extinct—until January 2019, when scientists found several specimens during an expedition to the northern Moluccas.

Wallace’s giant bee is the largest known bee species in the world. Females reach a body length of almost four centimeters and have a wingspan of 6.3 centimeters; the males are somewhat smaller. The species’ massive head is striking, broader than its thorax and bearing two oversized, protruding mandibles. The bee uses its mouthparts to scrape resin from trees for nest building.

Little is known about the distribution, lifestyle and habitat requirements of Wallace’s Giant Bee. All known specimens come from the three northern Moluccan islands of Bacan, Halmahera and Tidore. Because the islands are now covered with oil palm plantations and much of the bees’ natural habitat is likely destroyed, the conservation organization IUCN has classified Wallace’s giant bee as vulnerable on its Red List.