Scientists have discovered a new species of stick insect that may be the heaviest in Australia. The 40cm-long insect, named Acrophylla alta, weighs slightly less than a golf ball and was found in the high altitudes of the Atherton tablelands in north Queensland.
A peer-reviewed study published in Zootaxa journal noted that the stick insect is likely heavier than the giant burrowing cockroach, the current heavyweight champion of Australian insects. Researchers believe the cool, wet environment and high-altitude habitat could explain its large size, as body mass may help it survive cold conditions.
The discovery began with a social media post. Professor Angus Emmott of James Cook University said his co-author Ross Coupland was sent a photo of a stick insect and immediately suspected it might be something new. After many nights of searching, the pair found a large female between Millaa Millaa and Mount Hypipamee, so high in the canopy 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 identification. Emmott said the eggs are highly diagnostic, with each species having distinct characteristics. He believes the species remained undiscovered because its habitat is difficult to access, living high in the canopy unless brought down by storms or birds.
The next challenge is finding a male, which is proving difficult as males are significantly smaller and visually distinct from females. Emmott explained that finding a male copulating with a female is needed to confirm the pair belong to the same species. Queensland Museum entomologist Nicole Gunter said the discovery fills a gap in knowledge about Australia's biodiversity and highlights that up to 70% of Australian insect species remain undescribed. She stressed the importance of identification for conservation, noting the stick insect has so far only been recorded in a small number of forest localities in the wet tropics region of Queensland.
