A recently discovered species of giant stick insect has captured the attention of entomologists in Australia with its extraordinary size. Measuring around 40 centimeters (about 16 inches) in length and weighing roughly 44 grams, Acrophylla alta may be the heaviest insect ever documented in the country, surpassing the previous record-holder, the giant burrowing cockroach (Macropanesthia rhinoceros). Its official description, published in the journal Zootaxa, marks a notable addition to Australia’s exceptional insect biodiversity.
A Hidden Giant In The Rainforest Canopy
The discovery took place in the upland rainforests of North Queensland’s Wet Tropics Bioregion, a rugged area that includes Mt Lewis National Park, Evelyn Tablelands, Maalan National Park, Topaz, Upper Barron, Mt Hypipamee, and Danbulla. These high-altitude forests are notoriously difficult to access, which may explain why such a large insect remained unnoticed for so long.
According to Professor Angus Emmott from James Cook University, this insect thrives in a “cool, wet environment” where its substantial body mass may provide an evolutionary advantage, helping it survive colder conditions. Over millions of years, this environment likely drove the development of such an unusually large size. Despite its bulk, Acrophylla alta is an expert in camouflage, with a light brown coloration that allows it to blend seamlessly with branches and foliage.
A massive stick like insect nearly 16 inches long has been discovered in Australia. Meet Acrophylla alta, the country’s new heavyweight insect. pic.twitter.com/gE0ORB3PbE
— USA TODAY (@USATODAY) July 31, 2025
The Role Of Unique Eggs In Identifying The Species
The identification of Acrophylla alta relied heavily on its distinctive eggs. “Every species of stick insect has their own distinct egg style,” Emmott explained, noting differences in surface texture, pitting, shape, and even the structure of the caps. These details were key in distinguishing A. alta from other species within the genus Acrophylla, which was first described in 1835 and is found in regions including China, Australia, New Guinea, Tasmania, and nearby islands.
The research team, led by Emmott and Ross Coupland, first spotted the insect while searching high in the canopy of the Atherton Tablelands. In one instance, they used a long stick to coax a specimen down from the treetops. The largest individual they measured matched the extraordinary length of a human forearm, stretching from fingertip to elbow crease.
A Testament To The Importance Of Biodiversity Protection
Only two female specimens and their eggs are currently documented, both now preserved in the Queensland Museum for further study. This access will aid scientists in confirming the insect’s ecological role and refining conservation strategies for the unique rainforest habitats it calls home.
Emmott emphasized that understanding these ecosystems is essential for their preservation: “To conserve any ecosystem, we actually need to know what’s there, and what makes it tick, before we can think about the best ways to conserve it.” The researchers also believe there may be even more undiscovered species of stick insects — and potentially other insects — hidden in the dense, biologically rich rainforests of Australia.