Deep in the misty rainforests of North Queensland, where tree canopies stretch like green cathedrals, a monster has been found. A stick insect, 40cm long and as heavy as a golf ball, has been discovered in the high altitude forests of the Atherton Tablelands. Named Acrophylla alta, this is likely the heaviest insect ever recorded in Australia, a find that sounds like something from a prehistoric tale but is very much real today.

Angus Emmott, a researcher at James Cook University, didn’t stumble upon this giant by accident. It all started with a single photograph posted on social media that caught the eye of his colleague Ross Coupland. The image hinted at something unusual – a stick insect much bigger than any they’d seen before. They set out into the dense, wet tropics, spending many nights searching the tall trees between Millaa Millaa and Mount Hypipamee. Their persistence paid off when they spotted a massive female Acrophylla alta high in the canopy, so high they needed a long pole to coax her down.

This is no ordinary bug. At 16 inches long, it’s bigger than most of its kind, with a body so big it’s heavier than the giant burrowing cockroach, previously thought to be Australia’s heaviest insect at around 30 grams. The female Acrophylla alta weighed 44 grams, more like a small bird than an insect. Its big wings are impressive but not for flying – Emmott says they’re used more for gliding, the insect’s chunky body limiting it to gentle descents from the treetops.

What sealed the discovery as a new species was not just its size but its eggs. Stick insects are known for their unique eggs, each species producing shells with different textures, shapes and patterns. Emmott and Coupland collected the eggs laid by their captured female and through their intricate diagnostic features confirmed Acrophylla alta was a new species. These eggs are now part of the Queensland Museum’s collection along with two female specimens and will be a window into the insect’s biology and a tool for future research.

It wasn’t easy to find this insect and that’s no surprise. Acrophylla alta lives in a world most humans never see: the upper reaches of Queensland’s Wet Tropics, a UNESCO World Heritage site where trees grow up to 60m tall. These remote, high altitude forests, shrouded in mist and full of life, are hard to get to.

Finding a male Acrophylla alta is proving to be a challenge and it’s no wonder. Male stick insects are often smaller and visually different from females, sometimes so different they’re mistaken for a different species altogether. Emmott says confirming the male’s identity might require catching a pair in the act of mating – a tough ask in the dense canopy.
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