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Saving the World’s Rarest Insect

Jun 22, 2017 04:45 PM EDT

From the startling discovery of just 24 individuals in 2001, conservationists have brought the Lord Howe stick insect back from the edge of extinction.

Even as amazing insects go, it's pretty spectacular. People call it the land lobster, walking sausage, and tree lobster. It looks like a cross between a giant praying mantis and a cockroach. It is Dryococelus australis and at six inches long is almost the length of a human hand.

The walking sausage was once thought to be endemic to Lord Howe Island, a volcanic outpost 340 miles east of New South Wales in the Tasman Sea. For centuries the Lord Howe stick insect thrived among its lush vegetation.

But islands are notoriously precarious ecological habitats, and when the ship SS Makambo ran aground there in 1918, black rats entered the ecosystem. The results were catastrophic. Endemic animal species were wiped out. Native flora and fauna were destroyed. And every one of the Lord Howe stick insects was thought to have died, the species gone extinct.

But in 2001, two Australian scientists were studying the ecology of Ball's Pyramid, an island 14 miles across the open sea from Lord Howe. To call it an island is a stretch. It is a barren, nearly vertical volcanic rock that rises 1800 feet straight up out of the sea. The researchers had to be dedicated biologists and skilled climbers to study Ball's Pyramid.

To their wonder, they found the dead bodies of some Lord Howe stick insects.

A series of expeditions followed and one night (the insects are nocturnal as adults) scientists found two dozen living adults under a melaleuca bush. They had rediscovered a species thought to have been extinct for 80 years.

Astounded biologists around the world wanted to make sure we did not lose this unique species a second time. In 2003, a team of ecologists from the New South Wales National Parks and Wildlife Service collected two males and two females from Ball's Pyramid.

A breeding program was initiated at the Melbourne Zoo and at other sites in NSW. Success was hard-won, but by 2006 there were 50 living individuals. By 2008, over 700 individuals were thriving at the zoo and by 2012 there were 9000 walking sausages.

The insect has been reintroduced to Lord Howe Island under carefully controlled conditions.

Breeding programs are underway at the San Diego Zoo and in England at the Bristol Zoo. The species has been saved.

The hard work of preserving life is yielding scientific dividends. Extant individuals have supplied biochemists with cellular and mitochondrial DNA that were used in recent phylogenetic studies. The evolutionary lineage of the walking sausage and its relationship to other tree lobsters is now clear.

You may wonder how such a small population was able to survive for so long. The answer might lie in the species' reproductive capabilities. Females are often parthenogenic--they can reproduce offspring asexually.

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