The Species That Cheated Extinction: The Saga of the Lord Howe Island Stick InsectRead Now
Ball’s Pyramid is a rock monolith that thrusts its nearly vertical basalt walls 1,800 feet over the surface of the Tasman Sea between Australia and New Zealand. It is known as Ball’s Pyramid because it was discovered in 1788 by Royal Navy officer Henry Lidgbird Ball, who also discovered Lord Howe Island, situated 14 miles to the North. Ball’s pyramid, which is the world’s tallest sea stack (taller than the Empire State building), is the eroded remains of the caldera of an ancient volcano, and it was climbed for the first time in 1965 by a team of Australian rock climbers.
But Ball’s Pyramid is famous for an incident involving an insect. Island environments throughout the world due to their isolation have a special place in evolution. It is common to find on islands living things that are not found anywhere else in the world. Such was the case of the Lord Howe Island stick insect (Dryococelus australis), which could grow up to 6 inches long, and was often used as bait by the local fishermen.
Unfortunately, when a ship ran aground on Lord Howe Island in 1918, it introduced rats to the environment, and the rodents went on to wipe out the entire stick insect population. The last stick insect was seen in 1920, and after that year the species was thought to be extinct. Nevertheless, during the 1960’s, while climbing Ball’s Pyramid was still allowed by the Australian government, climbers sometimes reported that they saw carcasses of stick insects. However, these insects are nocturnal and nobody wanted to climb the jagged rock at night.
Finally in 2001 a handful of Australian scientists risked their lives in the darkness, and a few hundred feet above the waves on the sheer rock cliff they located a population of 24 of the famed Lord Howe Island stick insects eking a living on a few plants, which in turn were precariously growing in some cracks in the rock. After more exploration, they ascertained that these were the only stick insects on Ball’s Pyramid. Imagine that, the last 24 individuals left in the whole world of a species living in an environment that could be wiped out any day by a rock slide!
The insects managed to survive a few more years while the scientists battled the red tape of the Australian government before returning in 2003 to remove some pairs for breeding. The attempt was successful, and today there are thousands of descendants from those original breeding pairs. However, the newly bred Lord Howe Island stick insects looked different from specimens preserved in museums, and there was some question about whether they were a different but related species. Scientists solved this issue by applying the new tools of genomics to samples from the newly bred insects and those preserved in museums. It was determined that the newly bred insects differed genetically from museum samples by no more than 1%, which is how much samples from museum specimens differed from each other. This indicated that the newly bred insects and the original insects were indeed the same species.
Thus the Lord Howe Island stick insect had evaded extinction and come back from the brink thanks to a few daring and motivated scientists, and thanks to many generations of insects that clung tenaciously to life on the windswept spire of Ball’s Pyramid.
Image of Ball’s Pyramid by Fanny Schertzer is used here under an Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license. Image of the Lord Howe Stick Insect by Granitethighs is used here under an Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) license.