- Fiona Murdoch
- 23 October, 2025
- 9:09 am
- 0 comments
The Mallee Looper caterpillar that is eating the trees
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.
The outbreak became noticeable in 2022 when swathes of trees were defoliated in South Australia reserves like the Birdlife Australia Gluepot Reserve, Australian Landscape Trust Calperum Station and Danggali Conservation Reserve. In some places 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. Since then, the invasion has moved south and east into the Victorian Mallee.
Above left: An Arhodia sp. moth. Middle: The Mallee Looper caterpillar (Image: A.J. Dominelli) Below right: Arhodia moths in abundance attracted to a moth sheet (Image: Mark Hura)
What are we doing about the Mallee Looper?
Wildlife Unlimited is partnering with Mallee Conservation to research the Mallee Looper outbreak in Victoria. You can follow our progress here.
You can help!
Trap moths - We are expecting the Mallee Looper moths to emerge in November. If you live in the Mallee you can set up a cheap and simple moth trap. Counting the moths that you trap will help us understand distribution and abundance of Mallee Looper moths.
Report sightings - This summer in the Mallee keep your eye out for caterpillars defoliating Mallee Eucalypts. Take a photo and upload it to “Looking for Mallee Loopers” iNaturalist project.
A real team effort
Our project builds on the excellent work underway in South Australia, led by the Murraylands and Riverlands Landscape Protection Board.
The Mallee Looper knowledge we have is thanks to Toby Galligan (MR LPB) coordinating research efforts of so many: 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.
The Camel Pad walking track in Hattah Kulkyne National Park suffered defoliation by Mallee Looper caterpillars in early 2025. The above image shows the impacts. The image below was taken from the same location but looking towards unaffected trees. These will likely be impacted in 2026.
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.
Above left: A simple moth trap. Moths are attracted to the UV light then fall through the funnel into the bucket. They can be identified and counted in the morning. Below right: Defoliation on new growth of Eucalyptus oleosa (Image: Judy Allan).