One of the world’s largest moths has been officially reported in the US for the first time. Since Atlas moths, which have a wingspan of 25 centimeters (10 inches), are typically found in the tropical forests of Asia, entomologists are currency clueless about how the outlawed insect found itself in Washington. 

The moth was initially reported to the Washington State Department of Agriculture (WSDA) by Patrick C Tobin, an associate professor of ecology at the University of Washington, on July 7. The specimen was sent to the Animal and Plant Health Investigation Service at the United States Department of Agriculture (USDA) which confirmed on July 27 that it was, as suspected, an atlas moth.

“It was pretty amazing to see a live adult moth and to hold it in my hand. I teach a tropical ecology course in Costa Rica through my University, so I am used to seeing some pretty amazing insect species in the tropical forests. But seeing this live moth, which is considered to be the largest in the world, was special,” Tobin told IFLScience.

Atlas moths (Attacus atlas) are named after the Titan Atlas, who held up the heavens in Greek mythology, due to their colossal size. With a wingspan of over 25 centimeters, the species is one of the world’s largest lepidopterans, the order of insects that includes butterflies and moths. 

The species is considered a federally quarantined pest in the US, meaning it is illegal to obtain, harbor, rear, or sell live moths without a permit from USDA. This is because it could potentially become an invasive species, posing a risk to agriculture, the natural environment, or native species in the US. 

The tight restrictions put on this species make its appearance in the US even odder. 

"An individual from the Bellevue area of Seattle, from where the adult moth was found, was selling live cocoons of the Atlas moth sourced from Thailand on eBay. This is by far the most logical explanation for finding the adult moth," added Tobin. 

Atlas moths have been spotted outside of their natural range before. In 2012, a vast atlas moth was reported in the town of Ramsbottom in Greater Manchester, UK. In this instance, it was suspected that the individual had escaped from a private collection. 

If you’re in Washington and you think you’ve spotted an atlas moth, take a photo and send it to [email protected], along with some information about where it was spotted. Outside of Washington, you should report it to the State Plant Regulatory Official or State Plant Health Director in your state.

This article was amended to include quotes from Patrick C Tobin