Photo: Getty Images
The Lord Howe stick insect (Dryococelus australis), long believed to have gone extinct in the 1930s, has been rediscovered on a volcanic sea stack 23 kilometres from Lord Howe Island. Scientists have now confirmed that the population on Ball’s Pyramid is genetically identical to historical specimens, Forbes reports.
The species was once a common part of the Lord Howe Island ecosystem until ship rats arrived in 1918. The invasive rodents quickly decimated local fauna, and by the 1930s the stick insect was declared extinct. For decades, museum specimens were believed to be the last remaining evidence of the species’ existence. That changed in 2001, when a team of biologists climbed Ball’s Pyramid — a remote volcanic pinnacle nearly 550 metres high — and found live insects under a single Melaleuca howeana shrub. The insects looked darker and bulkier than museum samples, prompting years of scientific verification.
Definitive confirmation arrived in 2017, when a genetic analysis published in Current Biology revealed that the mitochondrial genomes of the Ball’s Pyramid insects differed from historical samples by less than 1% — exactly the amount expected within a single species over a century. This ended any remaining doubts and proved that the species had survived in an extremely narrow ecological refuge.
The insects persisted thanks to a combination of favourable factors: no rats or major predators on Ball’s Pyramid, and one resilient shrub that offered food and shelter. Recent studies also show that the species has biological traits that help tiny populations endure, including a slow reproductive cycle, long adult lifespan and efficient mating even at low densities.
In 2003, two breeding pairs were collected from Ball’s Pyramid to start a captive breeding programme. By 2016, more than 13,000 offspring had been produced. However, laboratory breeding revealed a hidden threat.
Studies published in 2018 and 2024 showed that captive insects are vulnerable to deadly bacterial infections such as Serratia marcescens and Pseudomonas aeruginosa. The major challenge now is preventing these pathogens from being introduced into the wild population during reintroduction efforts.
Meanwhile, Lord Howe Island has undergone significant ecological restoration. As Forbes notes, the island completed a full rat eradication programme in 2019, paving the way for the species’ return after more than a century of absence. Scientists are now preparing for reintroduction using genomic research, ecosystem modelling, pathogen risk assessments and restoration of host plants.
Once declared extinct and left forgotten in museum drawers, the Lord Howe stick insect survived on the edge of a volcanic cliff thanks to isolation, chance and remarkable resilience. Now, with continued scientific and conservation effort, the species has a real opportunity to return home and reclaim its place in the island’s ecosystem.
