Swarms of bogong moths across south-eastern Australia are raising hope for an endangered species. Authorities said the insects have blanketed homes and backyards in recent days, including in Sydney. Bogong moths have a wingspan of up to 5 cm. They migrate up to 3,000 km to caves in the Australian Alps each spring. The population collapsed by an estimated 99.5 per cent between 2017 and 2019. The species was listed as endangered in 2021. Drought, intensive farming and habitat loss drove the decline. This year has brought a comeback. Zoos Victoria’s Moth Tracker received 4,000 public submissions since September. More than 1,600 were confirmed as bogong sightings. That beats the previous best year of 1,089 in 2024. One theory is that extra rainfall in northern New South Wales gave larvae more food. The moths matter beyond their own survival. They pollinate eucalyptus trees and feed the critically endangered mountain pygmy possum. Researchers urge people to switch off outdoor lights and avoid insecticides. Moths found indoors can be gently released outside.