In the study, published Monday in the journal Current Biology, researchers said they found 88 nests across nearly 5 hectares (12 acres) near the Sicilian city of Syracuse during the winter of 2022-2023. There have been three “interceptions” of fire ants in Europe before — in Spain, Finland and the Netherlands — but this is the first time an extensive population has been identified on the continent, according to the study.

Fire ants are “one of the worst invasive species,” said the study’s lead author, Mattia Menchetti of the Institute of Evolutionary Biology in Barcelona, and they “can spread alarmingly quickly.”

The insects, which have the scientific name Solenopsis invicta, are known to spread by hitching rides on plants and boats, as well as by wind and water. (Tropical storms and hurricanes in the United States have forced warnings of floating ant islands in flooded areas.)

Locals told researchers that ant stings have been common in the area near Syracuse since 2019 — indicating that the fire ants have been present for some time.

Under current climate conditions, about 7 percent of Europe and parts of North Africa on the Mediterranean could make a suitable habitat for the ants, according to modeling done by the researchers. By 2050, the level of suitable habitat in the region could grow to more than 25 percent. Climate change, the study said, “will favor the expansion of this invasive ant.”

Invasive species are already proving costly around the world. A recent report backed by the United Nations found that more than 3,500 invasive species cost society more than $423 billion each year.

Scientists warn invasive pests are taking a staggering toll on society

Australia is spending millions of dollars on efforts to eradicate the fire ant from the continent, where scientists have warned that the invasive insects pose a threat to fragile and unique ecosystems, such as by eating seeds or fauna that nest or feed on the ground, or disturbing pollinating insects. According to a national eradication program, most areas of Australia are vulnerable to fire ant infestation. Only New Zealand has been successful in eradicating fire ants.

Aside from their impacts on ecosystems, fire ants can be a nuisance for humans, with bites that are known to be itchy and painful. In people with allergies to the ants’ venom, the bites can cause severe allergic reactions.

In June, a Georgia woman died after reportedly stepping on a pile of fire ants and suffering a fatal allergic reaction.