If you told the average person that a cockroach explosion was a sign of a healthy environment, they’d probably tell you to go wash your head. But down on Lord Howe Island, a speck of volcanic paradise sitting in the Tasman Sea, a massive spike in creepy-crawlies is being hailed as a triumph of nature. Seven years ago, this World Heritage site was crawling with an entirely different kind of pest—rats and mice. After the local authorities finished an eradication program that cleared out over 300,000 rodents in 2019, the island’s original inhabitants started coming out of the woodwork to claim their home back.
Maxim Adams, an honours student at the University of Sydney, has been tracking this invertebrate boom. He says the island is finally feeling alive again, with a 60 per cent increase in these little critters compared to before the cleanup. When he and the team from the NSW Department of Climate Change, Energy, the Environment and Water compared data from 2016 to their recent count, the numbers were startling. They went from collecting about 9,000 specimens in their first sweep to a whopping 15,000 in the second. When you stop rats from eating every bug in sight, nature does exactly what it’s supposed to do.
"It feels like the island is coming to life."
These bugs aren't just there to make your skin crawl; they’re the island's cleanup crew. They spend their days breaking down organic matter and turning it back into soil nutrients, which keeps the vegetation lush. They also serve as a vital snack for the island’s native predators, like the geckos and insect-eating birds that were struggling when their food source was being hoovered up by invasive rodents. The biggest success stories are the larger invertebrates, those over 13 millimetres long. These have seen population jumps that demonstrate the successful restoration of the food web.
It’s a bit of a poetic justice, really, seeing the big bugs finally getting their moment in the sun after years of being treated like an all-you-can-eat buffet for foreign pests.
Perhaps the most shocking reveal is the story of a native cockroach species once thought to be extinct. It turned up again in 2023, breathing hope into the conservationists who feared it was gone for good. While not every single species has made a full recovery, the island is moving toward a new, healthier balance. Professor Nathan Lo, who leads the Molecular Ecology, Evolution and Phylogenomics laboratory at the University of Sydney, says that while things won't be exactly as they were a century ago, the current trajectory is positive. He’s seen the results with his own eyes during night walks in the northern forests, where endemic geckos are now appearing in places they hadn't been spotted for decades.
There is plenty of work to do to understand how this new ecosystem will hold up in the long run. The researchers are now shifting their focus to the "higher-order" predators, like the geckos, to see how they’re adapting to this massive buffet of insects. To ensure nothing is missed, the team is also sequencing the DNA of the collected invertebrate samples. This high-tech approach will create a detailed biological blueprint of what is actually living on the island. That blueprint is a necessary component for future biosecurity efforts.
If they can figure out what is present today, they’ll have a much better chance of protecting these species from any future threats to the island's unique habitat.
Lord Howe Island is a small, isolated place, and these changes represent a delicate recovery. The rodent eradication was a massive, expensive operation, but seeing the woodhen and other native birds bouncing back alongside these bugs makes the effort a success. The team isn't just counting bugs; they’re watching the island reclaim its identity. It’s a rare piece of good news for the environment. It shows that when humans step back and fix their past mistakes, nature is often more than happy to do the rest of the heavy lifting.
The researchers will now conduct a deep dive into the DNA data, which will provide precise information about the island's biodiversity over the last decade.