What is the Mallee Looper?
The Mallee Looper is a caterpillar belonging to a moth in the Arhodia species complex. A species complex means that there are currently six or seven different moths all lumped together under the name Arhodia lasiocamparia.
The true A. lasiocamparia lives close to the coast in the east. All other moths are a different species and there are probably three species in north-west Victoria. I’m hoping there will be something obvious that distinguishes them, but at the moment it appears to be genital morphology! (1).
An Arhodia moth from the Victorian Mallee.
Why do we care about the Mallee Looper?
Back in 2021, a then unidentified 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. (Photo: Mark Hura)
Here in Victoria, we started to notice 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 the research here.
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.
Defoliation on fresh growth of Eucalyptus oleosa. Photo Judy Allan.
References and further reading
Arhodia taxonomy. There are several people involved in formally describing the Arhodia moths. Thanks to:
Dr Marianne Horak, Honorary Fellow, Australian National Insect Collection, and Dr Peter McQuillan, Senior Researcher University of Tasmania. There is currently a scientific paper in preparation describing the species in the Arhodia group.
Prof. Axel Kallies, all round legend, very generous on iNaturalist with his knowledge. Linking us “happy snappers” with the taxonomy of moths.
Peter MacNicol (1930-2019) with You Ning Su - early resolution that genital morphology defined the species.