Bringing the Top End’s massive moth back to the burbs
The atlas moth, a true marvel and emblematic species of the Northern Territory, remains a rare sight known only to a few.
Endemic to north-western Australia, the atlas moth (Attacus wardi) boasts an impressive wingspan of up to 22cm, making it Australia’s second-largest moth species – the largest being northern Queensland’s hercules moth (Coscinocera hercules) with a wingspan of a whopping 36cm.
Although teetering on the edge of extinction, this moth is not a flagship species. While classified as threatened in the Northern Territory, the atlas moth is not listed on Australia’s federal threatened species database, as is the case with most endangered invertebrates in Australia.
Changing fire regimes and the introduction of fire-promoting grasses have altered the habitats of the Top End’s monsoon forests and are the main reasons for a decline in atlas moth numbers. This vital and restrictive rapidly-shrinking habitat covers less than 0.2 per cent of the Northern Territory and is isolated to patches with permanent water sources or coastline.
Around Darwin itself, the atlas moth population faced a severe decline following Cyclone Tracy in 1974, compounded by extensive spraying of the insecticide Malathion to manage mosquito populations after the disaster.
With their naturally low dispersal ability, these moths struggled to recover and recolonise this habitat, unlike other more resilient species of moths and butterflies.
But one man has devoted his life to bringing the atlas moth back to Darwin. Lepidopterist and conservationist Geoff Martin is a builder by trade, with his past work taking him to remote areas of the Northern Territory. It was during a job in Milikapiti on the Tiwi Islands 20 years ago that he had his first encounter with an atlas moth – a glimpse of a singular wing from a male falling under a security light. The sheer magnificence of this wing alone ignited his passion, setting him on a course to help save the species.
Geoff now rears atlas moths in a pop-up monsoon forest in his garden in suburban Palmerston, 20km from Darwin, where he grows the four host plant species that atlas moth caterpillars depend on. Once matured, the moths are released to help re-establish wild populations. This is no easy feat, with the caterpillars needing attention for three months before turning into a moth.
Geoff nurtures the caterpillars from egg through to cocoon stage in a series of carefully managed enclosures. The real challenge begins when the moths emerge from their cocoons. Males live for just three to four days, and females five to six days. Crucially, females release pheromones for only the first two nights after emerging, which is the only time they are receptive to mating. Geoff faces a tight window of opportunity to hope that a female and a male emerge on the same day so they can mate. If successfully mated, the female will be ready to lay fertile eggs after a mating session that can last between 8 and twelve hours.
Once Geoff has successfully mated a female atlas moth, he releases her into one of the limited pockets of monsoon forests around Darwin. Here, she will lay fertile eggs that will hopefully grow to boost the local population.
After 12 years working to restore wild populations through his rear-and-release work, Geoff’s passion and commitment has motivated others to contribute to his mission.
Thanks to the dedicated efforts of volunteers and landcare groups, replanting atlas moth host plants in Casuarina Coastal Reserve https://landcarent.org.au/groups/casuarina-coastal-reserve-landcare-group/) is expanding monsoon forest and creating vital corridors in suburban areas. These initiatives aim to provide the necessary habitat conditions for this iconic moth to re-establish itself back in Darwin.
