Lord Howe Stick Insect: Extinct Species Back From the Dead After 100 Years

Adult female Dryococelus australis on hand. Rohan Cleave, Melbourne Zoo

An insect that was long taken for dead has been found. The Lord Howe Island stick insect, considered extinct for years, still walks—or crawls—the Earth.

Hungry rodents diminished their numbers long ago. When rats, stowing away on ships, came to Lord Howe Island, they found a tasty new food source in the Lord Howe Island stick insect. Rats ate so many that scientists believed these creepy crawlies had been eaten completely off the island.

The six-legged animal has never been found anywhere on Earth except for off the coast of New South Wales in Australia. It's born green, and as an adult, is dark brown and the length of a human palm. Some give this six-legged, flightless creature the endearing nickname of "tree lobster."

By 1920, conservationists declared the animal extinct. But in 2001, a team of entomologists and conservations exploring a nearby sheer volcanic stack called Ball's Pyramid discovered a few dozen stick insect specimens alive and well. Could this be the thought-to-be-extinct animal? Did this population use this inhospitable, steep rock in the Pacific to avoid the rats—and extinction?

Entomologists caught live individuals and brought them to zoos to start breeding programs, in the hopes that they could reintroduce the Lord Howe Island stick insect to the island from which it gets its name. The Lord Howe stick insect officially changed classification from "extinct" to "critically endangered."

But the newly bred bugs raised some doubts. They looked slightly different than the ones that had been declared extinct. They were lighter, had rounder heads and bottoms, and had thicker back legs. Only genetic testing could tell them for sure whether they were indeed the same species.

In research published today in Current Biology, zoologists compared DNA samples from the new population, derived from the insects found at Ball's Pyramid, with samples from museum specimens collected before their extinction was declared.

The verdict: yes, the two animals are one species. Dryococelus australis lives on.

The Lord Howe stick insect can now join the esteemed ranks of Lazarus Taxa, or animals formerly thought to be extinct. This group is named for Lazarus, a biblical figure who returned from the dead, and includes such animals as the coelacanth, a fish that was thought to have gone extinct in the Cretaceous, until modern animals were discovered in 1838.

The research has even broader implications. Conservationists hoping to return the insect to its former range can now rest assured that they would not be accidentally introducing an invasive species. It also highlights the importance of keeping museum samples of a variety of species for confirmation.

And now we know it's possible for species to avoid extinction by hiding on remote, obscure islets, away from human interference. And maybe they'll have a chance to go home again to their Australian island—but only if people exterminate the rats first.