Insect ‘detectives’ have discovered two new types of large stick insects, showing scientists are still uncovering new species in some of Australia’s most well-studied landscapes.

Researchers at the University of Sydney have revised the Australian representatives of the stick insect genus Anchiale, identifying two new species, one with unique ‘lidded’ eggs. They also reinstated a third species that had been hidden in plain sight for decades.

The findings reveal what were considered two species are five distinct species stretching in range from northern NSW through coastal Queensland and into the tropical north.

Despite more than 1000 citizen science observations of stick insects through iNaturalist and the Atlas of Living Australia, plus decades of scientific study, the researchers say Australia is still only scratching the surface of its insect diversity.

Lead author Dr Braxton Jones from the Aola Richards Sydney Insect Hub at the University of Sydney said the discovery highlights how much remains unknown about our insect biodiversity.

“Taxonomy is often a bit like detective work. Even among some of Australia's most photographed and frequently reported insects, we're still finding species that have escaped scientific recognition,” said Dr Jones, a Postdoctoral Research Associate in the Molecular Ecology, Evolution and Phylogenomics Laboratory.

One of the biggest surprises involved a large stick insect long known to scientists and insect enthusiasts. After combining DNA analysis, museum collections, surveys, citizen science records and studies of captive populations, researchers discovered the insect had been misidentified for decades. It is now recognised as an entirely new species, Anchiale robusta.

The findings are published in Austral Entomology.

The team also described Anchiale mabiensis, a new species found in Queensland’s critically endangered Mabi rainforest on the Atherton Tablelands. Its eggs contain a structural lid unlike anything previously recorded in stick insects or their closest relatives.

The research also has practical implications. A stick insect known for forming plague-like population outbreaks that can strip foliage from trees was found to consist of more than one species. Untangling those species relationships will help improve future management of impacts on forestry and agriculture.

The study even identified a likely additional undescribed species from Cape York, but more specimens are needed before its identity can be confirmed.

Dr Jones said: “These findings demonstrate the importance of protecting threatened ecosystems and documenting Australia's extraordinary biodiversity before we lose species without us having even discovered them.”

• Many stick insects can reproduce without ever mating with a male. This is called parthenogenesis, where a female produces eggs that develop into female-only offspring, clones of themselves. 
• Some stick insects can spray a chemical at predators when they feel threatened. The spray can irritate a predator’s eyes and mouth.
• Australia's longest stick insect is around 62cm (the world record is 64cm). There are 130 species in Australia and 3609 worldwide.
• Stick insects belong to a group called Phasmatodea, which comes from an ancient Greek word meaning “phantom” or “ghost.” They are so named because their incredible camouflage makes them seem to disappear like ghosts among vegetation.
• Some stick insects can gradually change colour to better match their surroundings, helping them blend into leaves, bark and branches. Colours range from greens to browns and even mimicking lichen. 
• Baby Extatosoma tiaratum stick insects have an incredible survival trick. When they hatch, the tiny nymphs have been found to emerge from ant nests looking and behaving as ants. The eggs can be carried into ant nests, where they remain dormant for months, protected from wasps. When they hatch, their ant-like colour, shape and behaviour help them scamper to the top of a eucalyptus tree unnoticed by predators.
• Some stick insects can suddenly flash brightly coloured wings when threatened, startling a predator. Some can also make a rustling sound with their wings, adding an extra level of startle to their wing morphology. 
• If a predator grabs a stick insect’s leg, some species can detach it on purpose to escape. This ability is called autotomy. Young stick insects can regrow the leg during their next moults, gradually replacing what they lost.

Main photo

Anchiale mabiensis (female) lives in Queensland’s endangered Mabi rainforest on the Atherton Tablelands. Stretched like this it is 16.3cm long. Photo: Angus Emmott, James Cook University

Research

Jones, B. et al ‘A revision of Australian Anchiale Stål, 1875 (Phasmida: Phasmatidae: Phasmatinae: Phasmatini), with the description of two new species’ (Austral Entomology 2026). DOI: 10.1111/aen.70096

Declaration

The authors declare no conflicts of interest. Funding for this research was provided by Australian Biological Resources Study – National Taxonomy Research Grant of the Commonwealth Department of Climate Change, Energy, the Environment and Water, and by CSIRO – postgraduate scholarship.