Federal customs officers were sifting through luggage at Detroit Metropolitan Airport last fall when they stumbled upon seed pods with little holes in them in one passenger’s bag. Inside, they found the larvae and pupae of an unidentified insect.
Now, staff at the U.S. Customs and Border Protection have determined that the larvae and pupae belonged to a moth species that hasn’t been seen for more than 100 years.
The rare moth saga began in September 2021, when customs agents in Detroit inspected the luggage of a passenger arriving from the Philippines. They found seed pods that the passenger said were for medicinal tea. When the agents looked more closely, they found exit holes that an insect inside the pods had apparently made.
The agents extracted larvae and pupae from the pods, then sent them off for testing and quarantine. Eventually, the larvae and papae matured into flashy moths with raised patches of black bristles, according to a statement from the agency. Though U.S. Customs agricultural specialists suspected the moths were a member of the Pyralida family, they couldn’t determine the genus or the species, so they sent the bugs off to the U.S. Department of Agriculture (USDA) for more analysis.
Entomologist M. Alma Solis, who specializes in moths for the USDA and Smithsonian Institution, examined an adult moth, as well as caterpillars and pupae. She determined the moths were Salma brachyscopalis Hampson, a species scientists last spotted in 1912 in Sri Lanka.
The moth pupae and larvae were likely brought into the country accidentally. As Alex Traub writes for the New York Times, experts say the species was "too obscure to possess the medicinal or aesthetic value that motivates smugglers.”
Each year, customs agents stop tens of thousands of potentially dangerous pests from entering the country via checked bags, carry-on luggage or vehicles. The moth discovery “is a testament to their important mission of identifying foreign pests and protecting America’s natural resources,” Robert Larkin, a federal port director, says in the statement.
Exactly how much damage the moths could’ve done, had they made it out of the airport, is unclear, but non-native bugs have the potential to inflict serious harm on crops and ecosystems.
Emerald ash borers have been killing North American ash trees for the last two decades, as Smithsonian’s Theresa Machemer reported in 2020, and along with other invasive insect species have the potential to kill more than 1.4 million urban trees by 2050 according to some estimates. Spongy moth caterpillars are eating their way through 700,000 acres of deciduous forests in the eastern United States per year, and spotted lanternflies are wreaking havoc on fruit trees and grapevines along the East Coast.“Would this moth have become the next multibillion-dollar pest?” Jason Dombroskie, a lepidopterist at Cornell University, tells the New York Times. “Probably not—but it’s possible.”