That's the message conservationists hope Australians will heed as they launch a new app to track sightings of the insect, in an effort to save a tiny possum from extinction.

The mountain pgymy-possum - Australia's only hibernating marsupial - wakes up each spring at their home in the Victorian and NSW alpine regions eager to munch the moths so they can raise their young.

But the critically-endangered species has been deprived of their favourite food for the past two years, with the bogong moths barely showing up.

That comes despite the moths migrating to the alpine regions from their winter breeding grounds throughout Queensland, NSW and western Victoria for more than 7000 years.

Experts don't know much about what kept the moths from their intended destination in the springs of 2017 and 2018, but it's believed light pollution from urban centres has played a significant role.

The moths use both the Earth's magnetic field and visual cues to help navigate their way, so light pollution can get them off course by sending them flying towards light sources.

To help keep the moths heading towards the mountain pgymy-possum, Australians are being urged to keep unnecessary outdoor lights off in September and October.

Zoos Victoria - which is spearheading the Lights Off for Moths campaign - also wants people to download Moth Tracker, an app where they can register bogong moth sightings.

Scientists will use the data to determine whether any moths are reaching the possums and what form their migration is taking.

Zoos Victoria wildlife conservation and science director Dr Sally Sherwen said the insights could mean the difference between life and death for the mountain pgymy-possum, of which only 2000 remain.

"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."

Some of the greatest beacons of light on the moth's flight path are Parliament House and Canberra's surrounds.

That means parliamentarians are among those being asked to keep unnecessary outdoor lights off when they're in town and use Moth Tracker.

The app can be accessed through any laptop or smartphone from Monday at zoo.org.au/possum.

It has been adapted from another app used to track sightings of the southern right whale, with Federation University and State Wide Integrated Flora and Fauna Teams involved in the project.

Australian Associated Press