How Do Bogong Moths Navigate Hundreds of Miles to Caves They've Never Seen?

Bogong moths navigate up to 600 miles across southeastern Australia each spring using the stars and the Milky Way as a compass — a feat confirmed by a 2025 study published in Nature by Lund University researchers, making them the first invertebrate ever proven to use a stellar compass for long-distance navigation.

The Journey: Billions of Moths, One Destination

Every spring, billions of Bogong moths (Agrotis infusa) lift off from the sun-baked plains of Queensland and New South Wales and fly south toward the Australian Alps. Their destination: a handful of specific cool granite caves tucked into the high country — caves the moths have never visited before in their short lives. Once they arrive, they pack the cave walls at densities of up to 17,000 moths per square yard, so thick the stone walls seem to ripple and breathe.

This is one of the most extraordinary insect migrations on Earth, and until recently, scientists couldn’t fully explain how the moths found their way with such precision.

Steering by Starlight: The 2025 Nature Discovery

In 2025, researchers at Lund University published a landmark paper in Nature confirming that Bogong moths navigate using a stellar compass — orienting themselves by the stars, including the structure of the Milky Way itself. This makes the Bogong moth the first invertebrate ever confirmed to use stars for directional navigation over long distances.

Previous research had shown that birds, sea turtles, and certain fish use celestial cues, but no insect had ever been confirmed to do the same. The Bogong moth doesn’t just sense light and dark — it reads the night sky.

The Brain Behind It All

Here is where the science becomes almost difficult to believe. The brain executing this celestial navigation is one-tenth the volume of a single grain of rice. That minuscule cluster of neurons — a few hundred thousand cells at most — is processing star patterns, calculating direction, and guiding the moth accurately across hundreds of miles of unfamiliar terrain.

This challenges longstanding assumptions about what complexity of brain is required for sophisticated spatial navigation. The Bogong moth suggests that neural efficiency, not size, may be the more important variable.

An Ancient Human Connection

Long before scientists studied the moths, Aboriginal peoples including the Dhudhuroa and Ngarigo nations tracked the Bogong moth migration with precision. Each summer, groups traveled into the high mountains to harvest the arriving moths — a rich, fat-dense food source that drew nations together for ceremony and trade. The moths’ arrival was so reliably seasonal they functioned as a living calendar, a biological clock written in wings across the sky.

This convergence of ecological and cultural knowledge stretches back thousands of years, making the Bogong moth one of Australia’s most culturally significant insects.

A Population in Crisis

The same migration that sustained ecosystems and cultures for millennia is now in jeopardy. Between 2017 and 2019, Bogong moth populations collapsed by over 99% at some monitoring sites. The causes are complex — drought, habitat loss on breeding grounds, and light pollution that may interfere with their stellar navigation.

The consequences ripple outward. Mountain pygmy possums (Burramys parvus), a critically endangered species, depend on the fat-rich moths to build up energy reserves before winter. Without the moths, possums starve. One insect, one star compass, and an entire alpine food web hangs in the balance.

Why This Matters Beyond the Moths

The Bogong moth story reframes several big questions at once: What is the minimum neural hardware required for complex navigation? How did stellar compass orientation evolve across the animal kingdom? And what happens to ecosystems — and the cultures woven through them — when a single keystone species disappears?

The answers, it turns out, may be written in the night sky above the Australian Alps.