News from the underground

Each year, billions of Australian Bogong Moths, Agrotis infusa, undertake a perilous, long-distance migration to a small selection of alpine caves in the Australian Alps, caves that these insects have never been to before. 

Their journey begins in spring, after emerging from their pupae the newly adult moths embark on their migration, covering over 1000 km, from the dry plains of southern Queensland, New South Wales and Victoria to the Australian Alps. A journey lasting days or even weeks. Once in the Alps, Bogong moths seek out the shelter of a select few isolated caves on high ridge tops and rock crevices, typically at elevations above 1800m. Towards the end of the summer, the same moths that arrived months earlier, leave the caves and begin their long return trip to their breeding grounds back on the dry plains. Once there, the moths mate, lay eggs and die. The following spring, the eggs hatch and the moths begin this cycle again. Despite having no experience of the route and no parental teaching, these moths find their way to this very specific selection of caves. So why do these moths seek out these caves? And how do they navigate a route they have never flown before? 

What makes these caves so special?

Over the summer months, hundreds of thousands of moths line the interior walls of these cool high alpine caves, where they estivate (a form of hibernation) for up to four months. This summer estivation helps delay the breeding season so that eggs do not hatch into an environment with poor food and high temperatures.

On route to the Alps, Bogong moths don’t appear to use other caves as temporary (or permanent) shelters, even when available and at suitably high elevations, instead using tree hollows and boulder fields as temporary shelters. Once in the Alps, suitable caves are identified by a unique odour coming from the caves, providing a beacon at the end of their long journey. It is speculated that this smell may be caused by the remains of countless dead moths from previous generations, or from pheromones produced from moths already at a site. 

Navigation in the dark

How these moths manage this remarkable journey has been a topic of debate for many years. Research has shown that these moths navigate using a combination of the Earth’s magnetic field and the starry night sky, as a compass, guiding them to their distant destination. While these appear to be the main mechanisms used, others are still under investigation. At the recent (October 2025) Perth Biodiversity Conference, Dr Eric Warrant, presented recent research undertaken by his team, including experiments testing the moths navigation skills with one or both of these factors turned off. Their research is ongoing, with plans to investigate the brain processes in these moths, and how this specific journey has been programmed into their genetic code. 

Learn some more: 

• Dreyer et al. (2025) Bogong moths use a stellar compass for long-distance navigation at night (https://www.researchgate.net/publication/392798357_Bogong_moths_use_a_s…)
• Warrant et al. (2016) The Australian bogong moth Agrotis infusa: A long-distance nocturnal navigator (https://www.researchgate.net/publication/299864332_The_Australian_Bogon…)

In 2026 we featured the Troglodiplura genus as the Australian Cave Animal of The Year. In our website information, and now included in this new website, we included that all five of the currently known species of Troglodiplura are only known from juvenile specimens, or from small broken fragments of adult males and that no living adult males have been recorded.

A recent communication with cave biologist Dr Jess Marsh confirmed that there’s still be no sighting of an adult male. Dr Marsh writes: 

We still haven’t seen a living male Troglodiplura, although we reecently went to a cave with hundreds of old, dead mummified males, so have a good handle on what they look like now. It was a bizarre cave, and we aren't sure why there were so many dead males. Their biology is all still a mystery, but I suspect the males are active at a time of year that there is less visitation on the Nullarbor (either mid-summer or, more likely, mid-winter). Still, something to investigate. We have found some more caves with living Troglodiplura in them, maybe new species, so that is exciting, and good for conservation. 

It’s happened. After much effort from many people, and especially Hadja Zupan-Hajna from the International Union of Speleology, UNESCO recently proclaimed 13 September as the International Day of Caves and Karst.

The International Day of Caves and Karst will help raise global awareness of caves and karst, including cave fauna. Did you know that caves and karst cover nearly one quarter of the Earth’s land surface and provide drinking water to over a billion people. They preserve unique subterranean biodiversity, geological archives and invaluable cultural heritage. Despite this, caves and karst are amongst the least understood and most fragile ecosystems on planet Earth.

Find out more at: https://uis-speleo.org/index.php/2025/11/13/unesco-proclaims-the-international-day-of-caves-and-karst/