The Lord Howe Island stick insect (Dryococelus australis) is one of the world’s rarest insects. Once thought to be extinct for nearly a century, this species has been rediscovered and has captured the attention of conservationists and entomologists alike.
The Lord Howe Island Insect
Known as the “tree lobster”, the Lord Howe Island stick insect is the largest flightless stick insect in the world (roughly five inches long), has a hard, glossy exoskeleton and is nocturnal. It spends its day in tree hollows, congregating in large groups of around 60 individuals in a single hollow. Its slow movements and inability to fly made it particularly easy prey for rodents.
The Insect’s Extinction
The Lord Howe Island stick insect was considered extinct in 1920 after Black rats were introduced to the island in 1918. The rats found a home on the island after the SS Makambo ran aground on its shore. The result was an incredible ecological disaster, which saw five species becoming extinct because of the invasive rodents.
The Remarkable Rediscovery
In the 1960s, whispers of the species’ return surfaced, but they were not confirmed until 2001 when climbers exploring Ball’s Pyramid reported finding recently dead stick insects. Ball’s Pyramid is a steep and rocky islet south of Lord Howe Island. This discovery was completely unexpected, as the jagged seaside cliffs seemed a haven for the creatures.
An Expedition To Prove Extinction
After the reports from the hikers, David Priddel and Nicholas Carlile, from the NSW Government’s Office of Environment and Heritage, wanted to prove that the Lord Howe Island stick insect was indeed extinct. The expedition resulted in the opposite of its intent – Priddel and Carlile’s team found three live Lord Howe Island stick insects nestled in a narrow crevice in some tea tree bushes.
How Had They Survived?
The Lord Howe Island stick insects’ population was precarious, with only 24 individual insects found in total. The insects survived by relying on a single bush that provided food and shelter. Researchers still do not know how they came to be on Ball’s Pyramid, some 14 miles from Lord Howe Island.
Ecological Importance
The stick insect is considered ecologically important as a “keystone” species. Keystone species help determine the ecological health of any given area. The Lord Howe Island stick insects are herbivores and, therefore, play a vital role in their ecosystem by contributing to plant health and serving as prey for other species. Additionally, the species is parthenogenic (females can reproduce with males), which could explain its remarkable survival and aid in future breeding efforts.
Conservation Efforts
In 2003, Lord Howe Island Board staff collected two pairs from Ball’s Pyramid and sent them to Melbourne Zoo to establish a captive breeding program. These programs aimed to increase their numbers and eventually reintroduce them to their native habitat. Today, 800 adults and 19,000 eggs have been hatched in Melbourne Zoo. Specimens have been moved and bred in several zoos around the world.
Breeding the Insect
From 2012, zoos worldwide began breeding Lord Howe Island stick insects to increase population and establish insured populations. The Budapest Zoo was the first zoo outside of Australia to reproduce the insect, and it was followed by zoos in England, the United States, and Canada soon after.
Reintroduction to Lord Howe Island
Reintroduction began in 2008 when 20 individual insects were returned to a special habitat on the island. Once the island’s rat problem was addressed, plans were made to release some onto Blackburn Island, an islet in the Lord Howe Lagoon, in 2023. This release was an experiment to test the success of reintroduction to the larger island.
Reintroduction Challenges
The discovery site was monitored by the Lord Howe Island Board, and when a five-leaf morning glory vine overgrew the area where the initial insects were found, the Board organized for the vine to be removed to secure the remaining populations on Ball’s Pyramid. Additionally, the Lord Howe Island Rodent Eradication Project was implemented in 2019. The program aimed to remove rodents from the island entirely using rodenticides.
The Insect’s Future
Researchers believe that close consultation with local communities and further research into the species’ ecology, genetics, and disease risk will be important in reintroducing and conserving these insects. With populations thriving in captive breeding programs worldwide, the insect is expected to recover remarkably from near extinction.
A Beacon of Hope
With the rediscovery and reintroduction of Lord Howe Island stick insects into the wild, scientists and conservationists around the world are collaborating to reestablish a unique creature in an ecological system known for its incredible biodiversity. In doing so, they are helping to repair the damage of the past.
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