A newly discovered stick insect measuring 40cm in length and weighing slightly less than a golf ball may be the heaviest insect in Australia, scientists have said. The species, named Acrophylla alta, was found in the high altitudes of the Atherton Tablelands in north Queensland.
The peer-reviewed study published in Zootaxa journal notes that the stick insect is likely heavier than the giant burrowing cockroach, currently the heaviest insect in Australia. Researchers believe its large size may be an adaptation to the cool, wet environment where it lives.
James Cook University researcher Professor Angus Emmott said a social media post helped with the discovery. His co-author, Ross Coupland, was sent a photo of a stick insect and immediately suspected it might be a new species. After many nights of searching, they found a large female between Millaa Millaa and Mount Hypipamee, so high in the canopy that they had to use a long stick to retrieve it.
The researchers kept the female in a cage, fed it, and collected its eggs for further study. Emmott noted that stick insect eggs are very diagnostic, with each species having slightly different eggs. He believes the species had not been discovered earlier because its habitat is difficult to access, living high in the canopy where only cyclones or birds might bring specimens down.
The next step is finding a male, which is proving difficult because male stick insects are significantly smaller and visually distinct from females. Emmott explained that finding a male copulating with a female would confirm the pairing. Queensland Museum entomology expert Nicole Gunter said the discovery fills a gap in knowledge about Australia's biodiversity and highlights that up to 70% of Australian insect species are currently undescribed. She stressed that recognising the species is important for its conservation, as it has so far only been recorded in a small number of forest localities in the wet tropics region of Queensland.
