A new online tool has been launched to help monitor bogong moth numbers in what is shaping up to be a crucial season for both their migration and a food source for the critically endangered mountain pygmy possum.

Key points: Bogong moths have been migrating to alpine Australia for over 7,000 years

Bogong moths have been migrating to alpine Australia for over 7,000 years About 4.4 billion moths participate in the migration but in the last two years the insects have all but disappeared

About 4.4 billion moths participate in the migration but in the last two years the insects have all but disappeared The moths provide a vital food source for the mountain pygmy possum, which have dropped in numbers to about 2,000 since the bogong moth decline

Each spring about 4.4 billion bogong moths head to the country's alpine regions in south-east New South Wales and north-east Victoria — the biggest injection of nutrients into the area second to sunshine.

But in 2017 and 2018 the billions of bogong moths that have been migrating for over 7,000 years from their winter breeding grounds throughout Queensland, NSW, and western Victoria almost completely disappeared.

The moths are a staple food source for the mountain pygmy possum that in monitored areas have been showing signs of stress with low body weight and high infant mortality rates since the moth numbers plummeted.

The disappearance of the moths puts pressure on the already struggling possums, with only around 2,000 remaining in the wild.

An endangered mountain pygmy possum from Victoria's Healesville Sanctuary. ( Supplied: Zoos Victoria )

Zoos Victoria has launched the Moth Tracker website that will allow the public to photograph and log any potential sightings of migrating bogong moths this spring.

Researchers have outlined concerns that little is known about the movements of moths despite their environmental and cultural significance, and are hoping citizen scientists will now be able to help provide more of an understanding about the insect.

"Citizen scientists, particularly over a large area like the bogong moth migration [area], are really important," said Zoos Victoria reproductive biologist Marissa Parrott.

"We haven't tried to run a program like this before at Zoos Victoria, but we know that there have been great results from overseas when people all work together.

"It's extremely important that we can start to fill those knowledge gaps that we have about the migration, and about how and when and where the moths are moving."

Wildlife conservation and science director at Zoos Victoria, Sally Sherwen, said Moth Tracker data will be used to help bridge those knowledge gaps.

"Moth Tracker is a simple and practical way for everyday Australians to join in this fight to save these tiny, adorable and very precious mountain pygmy possums," Dr Sherwen said.

"The easy-to-use platform will provide scientists with real-time data that will be contributing to saving a species."

Billions of bogong moths normally line the walls of alpine caves during summer. ( Supplied: Dean Heinz )

A tense season ahead

The newly-launched tracker coincides with the start of the moths' spring migration.

It also builds on the Lights Off for Moths campaign, which works to prevent moths from becoming diverted and trapped in bright cities over September and October.

The tool will be used to give researchers an early indication of the season ahead.

"Given the issues that bogong moths are facing with those massive and worsening droughts across south-eastern Australia, as well as changed agricultural practises, and artificial night light we're seeing across south-east Australia, we know that the bogong moths have been in real trouble," Dr Parrott said.

"This year is looking like another bad year that we saw last year."

Bogong moths migrate from as far as Queensland each year to alpine NSW and Victoria. ( ABC Open contributor Nick )

A bad season for moth numbers would also mean a tough year ahead for the endangered possums, prompting the Mountain Pygmy Possum Recovery Team conservation group to consider implementing interventions in the wild.

This could include supplementary feeding, improving habitat connectivity, and captive measures to support populations through the breeding season.

Dr Parrott said funding was needed to better understand the moths and help prevent their decline.

"It's really important we increase the funding for animals like bogong moths," she said.

"They don't attract the level of funding that other species, like the mountain pygmy possum or the Tasmanian devil are able to attract, yet the bogong moth is so important.

"It's important in its own right, we need to protect the bogong moth, and also for other species in the alpine zone."

The Moth Tracker is available through the State Wide Integrated Flora and Fauna Teams (SWIFFT) website.