‘Thrilled’: huge swarms of bogong moths surprise NSW residents and may point to species’ recovery

Unusual swarms of bogong moths have been observed across New South Wales in recent days, sparking cautious optimism among conservationists regarding the endangered species’ potential recovery.

Citizen scientists participating in the Bogong Watch initiative—managed by Invertebrates Australia—have recorded hundreds of moth sightings throughout coastal regions over the weekend via the iNaturalist platform.

The phenomenon coincides with spring, marking the onset of the bogong moth’s annual migration. Each year, billions of these insects travel up to 1,000 kilometers to remote alpine caves in the Australian Alps, seeking refuge from rising temperatures during summer months.

Linnea Emneby, coordinator of the Bogong Watch program, noted that volunteer “sentinels”—positioned strategically around Mount Kosciuszko—have reported unusually high moth activity. One observer documented over 200 bogongs on a single night last Sunday, while multiple households reported clusters of dozens of moths on Monday.

Standing roughly the size of a 50-cent coin and weighing less than half a gram, bogong moths serve vital roles within ecosystems—notably as pollinators and a key food source for the critically endangered mountain pygmy possum.

“We’re absolutely thrilled with what we’re seeing,” said Dr. Marissa Parrott, a reproductive biologist at Zoos Victoria involved in the Moth Tracker project. “Sightings this season far exceed expectations—we’ve already received more reports in September than we did throughout all of last year.”

She added, “This surge in numbers strongly suggests a positive trend in population recovery, particularly across New South Wales and the ACT regions. However, Victoria continues to lag behind.”

Parrott attributed favorable climatic conditions—including cooler and wetter weather—to the recent increase in moth activity. She emphasized that migrations occur in waves, with some individuals taking extended periods to reach their alpine destinations.

“This pattern aligns with historical norms,” she explained. “Large-scale movements like these used to occur regularly across southeastern Australia, including cities like Sydney, Canberra, and Melbourne.”

Historically, billions of bogong moths undertook this journey annually. However, between 2017 and 2019, populations plummeted by as much as 99.5%, leading to its classification as endangered by the International Union for Conservation of Nature in 2021.

As nocturnal creatures, bogong moths navigate using starlight—a trait unique among invertebrates. While many follow established migratory corridors, others may become disoriented due to shifting wind systems, occasionally straying beyond intended paths—even reaching nearby islands such as New Zealand.

“Despite concerns surrounding ongoing drought conditions linked to El Niño events, current indicators suggest promising short-term prospects,” Parrott said. “We remain vigilant about future challenges if adverse climate trends persist.”

Experts encourage residents encountering bogong moths to minimize lighting at night, avoid pesticides, and report sightings through dedicated platforms like Moth Tracker or Bogong Watch.

“Should moths enter homes, handle them gently and release outdoors,” advised Parrott. “With females capable of carrying up to 2,000 eggs, preserving each individual contributes significantly to species recovery efforts.”

“These creatures pose no threat—they neither inflict harm nor damage property. On the contrary, they support plant pollination and enrich garden biodiversity. Ultimately, they’re harmless and will continue their journey independently.”

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