• Fiona Murdoch
  • 29 September, 2025
  • 2:32 pm
  • 0 comments

The butterflies are nearly here!

Meanwhile, in the Mallee … Wildlife Unlimited ecologist, Fiona Murdoch is anxiously awaiting the emergence of this year's Mallee Bronze Azure butterflies (Ogyris subterrestris).

“We know from our long-term dataset that these rare butterflies emerge in early October. Over the past four years they have appeared on the 3rd, 8th, 16th and 11th, so it is pretty consistent.” says Fiona.

However, since the Murray River flood in December 2022, the abundance of butterflies has declined and several subpopulations in Hattah Kulkyne National Park have disappeared. The butterflies were abundant at these locations in 2022, prior to the flood. Over the past two seasons Wildlife Unlimited ecologists have searched these areas extensively, but there has been no sign of the butterflies.

Above left: A female Mallee Bronze Azure butterfly. Middle: Detail of dew on a butterfly wing. Did you know butterfly wings are covered in scales?! Below right: Detail of a butterfly head. The hairy, moustache-like appendages are the labial palps, important sensory organs. All images: Current Line Productions.


Protecting a threatened species

In response to this decline, we led a nomination for the species to be listed under the federal Environment Protection and Biodiversity Conservation Act 1999. In September, the Threatened Species Scientific Committee confirmed the nomination had been accepted and the butterfly has been prioritised for assessment.

The Mallee Bronze Azure butterfly has a unique lifestyle that makes it vulnerable to flooding. The butterflies fly and mate during October and November then lay eggs at the entrance to a nest of their host Sugar Ant Camponotus terebrans.

The caterpillar is cared for by the ants but in a strange twist, we think it feeds on the ant larvae! It remains underground in the ant nest until it emerges as a beautiful butterfly.

Fiona is looking forward to adding to our long-term dataset this year. “Nothing better than clambering around under bushes counting tiny butterfly eggs whilst ants crawl all over you!”


Senior field ecologist, Fiona Murdoch, searching for the eggs of this threatened butterfly.


Surveys in 2023/24 were jointly funded by the Australian and Victorian governments under Disaster Recovery Funding Arrangements. Surveys in 2024/25 were part of the Victorian Murray Floodplain Restoration Project for Mallee CMA and the Arthur Rylah Institute.

Above left: A mating pair of Mallee Bronze Azure butterflies, female on top. Below right: A Sugar Ant with tiny butterfly eggs, they are less than a millimeter in diameter! Both images: Current Line Productions