What is the Mallee Looper?
The Mallee Looper is a caterpillar belonging to a moth in the Arhodia species complex. These caterpillars are eating their way through thousands of hectares of Mallee Eucalypts.
An Arhodia moth from the Victorian Mallee.
Why do we care about the Mallee Looper?
Back in 2021, this caterpillar became superabundant and started defoliating Mallee Eucalypts in South Australia. Areas like the Birdlife Australia Gluepot Reserve, Australian Landscape Trust Calperum Station, and Danggali Conservation Reserve were hit hard.
The defoliation became apparent in December and January and in some areas it looked like a fire had burnt through the area. Although the affected trees regrew their leaves, they were hit again by caterpillars in subsequent years.
2023 was a particularly bad year with reports of up to 150,000 - 250,000 hectares affected. In January of that year, Dr Peter McQuillan identified the culprit as an Arhodia caterpillar and named it the Mallee Looper.
The Mallee Looper caterpillar pretending to be a twig. The head end is in the air. (Photo: Mark Hura)
Here in Victoria, we noticed extensive areas of defoliation in Murray Sunset National Park in early 2022 and 2023. Affected areas have been smaller in subsequent years, but the infestation appears to be moving south and east. In January 2025, the caterpillar hit Hattah Kulkyne National Park and the Raakajilm conservation property.
Camel Pad Walking Track in Hattah Kulkyne National Park in February 2025. The trees have been completely defoliated by the Mallee Looper caterpillar.
Photo taken from the same location in Hattah Kulkyne National Park but looking into Mallee woodland not affected by the Mallee Looper. These trees will likely be hit in early 2026.
What are we doing about the Mallee Looper?
Friends of Mallee Conservation is partnering with Wildlife Unlimited to research the Mallee Looper outbreak in Victoria. You can keep up to date with our research through our Mallee Looper blog.
What can I do?
Trap moths - If you live in the Mallee you can set up a cheap and simple moth trap. This will help us understand where and how many Mallee Looper moths are about. See DIY Moth Trap
Report sightings - This summer in the Mallee keep your eye out for caterpillars defoliating Mallee Eucalypts. Take a photo and upload to “Looking for Mallee Loopers” iNaturalist project.
And in South Australia?
Our project builds on the excellent work underway in South Australia, led by the Murraylands and Riverlands Landscape Protection Board. My eternal gratitude to Toby Galligan for summarising South Australia knowledge to date, and establishing the “Looking for Mallee Loopers” iNaturalist project.
Galligan, T. (2024) Mallee Looper investigation 2023/24. Murraylands and Riverlands Landscape Protection Board summarises life history knowledge to date, gathered from entomologist Dr. Peter McQuillan, ecologist Dianne Pearson, and researchers and volunteers at Birdlife Gluepot Reserve, Australian Landscape Trust Calperum Station, and iNat legends like Ellura Sanctuary and Rhytiphora.
Defoliation on fresh growth of Eucalyptus oleosa. Photo Judy Allan.
This project of the Regional Drought Resilience Planning program is jointly funded through the Australian Government’s Future Drought Fund, the Victoria Government and the Natural Resources Conservation Trust.