Having been wiped out in their homeland, Lord Howe Island stick insects now live on the world’s tallest sea rock pillar and there are only about 9 – 35 left.
Despite facing many threats, the Lord Howe Island stick insect still exists. Image: Granitethighs/Wikimedia
Rare and endangered animals often hide in hard-to-reach places. Sometimes they only live in a small area. With the world’s rarest insect, the Lord Howe Island stick insect (Dryococelus australis), also known as the tree lobster, is home to an uninhabited sea rock column in the Pacific Ocean. Their survival story is quite special.
With a dark body, 6 long legs and a body length of 15 – 20 cm, the Lord Howe Island stick insect looks quite like a prehistoric creature. Initially, this animal was only found on Lord Howe Island in the Tasman Sea, between Australia and New Zealand. In 1918, the cargo ship SS Makambo sank here and accidentally caused an ecological disaster, causing the island to be invaded by black rats.
Rats cause big problems for native creatures, including stick insects. It is thought that they were wiped out around 1920. In addition to stick insects, rats also wiped out five species of birds, at least 13 species of invertebrates and two species of plants on the island.
But in the 1960s, climbers visiting Ball’s Pyramid found the remains of molting stick insects. Ball’s Pyramid is a small uninhabited rock column, formed from a steep volcanic block 23 km from Lord Howe Island, and is the tallest sea rock column in the world.
“It’s quite a bare landscape. There’s not a lot of land on it,” said Kate Pearce, invertebrate life sciences manager at Melbourne Zoo.
Ball’s Pyramid is home to the world’s only wild population of Lord Howe Island stick insects. Image: Ashley Whitworth
The stick insects at Ball’s Pyramid are not really like those at Lord Howe. They have smaller legs and darker colors. With some confusion, the International Union for Conservation of Nature (IUCN) Red List officially declared the animal extinct in 1986.
However, the story does not end there. In 2001, an expedition team went to Ball’s Pyramid to clarify the climbers’ reports. They found feces, then three individuals living on a tea tree 64 meters above sea level.
This discovery led to a captive breeding program of four individuals collected in 2003. DNA analysis confirmed they were Lord Howe Island stick insects. A pair of beetles named Adam and Eve were brought to Melbourne Zoo to start a breeding program.
By 2022, thanks to the Melbourne Zoo program, nearly 19,000 individuals have been born. This species also lives at the San Diego Zoo and visitors are invited to observe them in a specialized environment in late 2023.
According to the IUCN Red List, Lord Howe Island stick insects are still critically endangered, with the number of wild individuals only about 9 – 35. The main threats are storms and drought due to the population size being too large. small. They depend on melaleuca bushes (Melaleuca) in Ball’s Pyramid and the plant itself is threatened by invasive vines. Poaching can also lead to extinction.
A comprehensive inspection in July 2023 showed that no rats had lived on Lord Howe Island for more than two years, marking an important milestone in the rat extermination campaign. Experts hope that in the future, rare stick insects can be released back to their original homes.