Australia is home to many extraordinary creatures, from Antarctic emperor penguins washing ashore to the largest great white shark ever recorded. Adding to this list of oversized wonders, construction workers in Queensland recently made an astonishing discovery: a giant wood moth, described as being “the size of two fists put together.”
The moth was found by accident at Mount Cotton State School, located on the edge of a rainforest. According to Megan Steward, the school’s principal, it is not unusual to see wildlife around the school, including bush turkeys, wallabies, koalas, ducks, snakes, echidnas, tree frogs, possums, chickens, and turtles. However, no one had ever seen a giant wood moth on school grounds before.
According to ABCNews, the moth was so large and heavy that it could not fly. After taking photographs, the construction workers carefully moved it to a nearby tree, hoping it would lay eggs or find a mate.
“We have a range of animals on our grounds at Mount Cotton State School… But a giant wood moth was not something we had seen before.” – Megan Steward
Students were not present at the time of the discovery but later saw photographs of the massive moth and were even asked to write stories about it as part of a school project.
The World’s Heaviest Moth
The giant wood moth (Endoxyla cinereus) is officially the heaviest moth in the world. It is found in Australia and New Zealand, two regions known for hosting larger-than-life wildlife.
A fully grown giant wood moth can weigh up to 30 grams and have a wingspan between 15 and 25 centimeters (6-10 inches). This incredible size is due to its long larval stage, during which it feeds on eucalyptus and acacia trees.
Females are particularly heavy, as they can carry up to 20,000 tiny yellow eggs at one time. Because of their sheer weight, female moths struggle to fly and instead crawl from one location to another, waiting for a mate.
Why Are Giant Wood Moths So Rare?
Despite their size, giant wood moths are rarely seen. This is because they spend most of their lives hidden as larvae inside trees before emerging as moths for a very short adult lifespan.
The life cycle of the giant wood moth begins when the eggs hatch and larvae spin silk threads to float away on the wind. The larvae then burrow into the ground, feeding and growing, though how long they remain underground is still unknown.
When large enough, they climb trees and bore into the bark, sealing themselves inside with a gelatinous substance for protection. The larval stage lasts up to three years, during which they feed on tree sap and grow into massive sizes.
Once fully grown, they undergo metamorphosis and emerge as adult moths. However, as adults, they cannot eat and only live for a few days—just long enough to reproduce before dying. This extremely short adult lifespan makes seeing a live giant wood moth incredibly rare, especially one as large as the specimen found in Queensland.
Environmental Threats to the Giant Wood Moth
While not officially endangered, giant wood moths face serious environmental threats that could reduce their population in the near future.
The impact of climate change on giant wood moths is not fully understood, but scientists suspect that rising temperatures are accelerating their development. This means they spend less time in their larval stage, potentially preventing them from growing to their full size. If this trend continues, the number of large giant wood moths could decline significantly.
Deforestation is another major threat. The giant wood moth relies on rainforests in Australia and New Zealand for survival. However, the destruction of these forests is leading to fewer trees for larvae to burrow into and an increased risk of larvae being killed when trees are cut down before they mature.
Since it takes up to three years for a larva to become an adult moth, the removal of eucalyptus and acacia trees puts the species at risk.
