The USDA put out a warning about the New World Screwworm on Wednesday.

New World Screwworm larvae (maggots) can burrow into the flesh of a living animal and cause serious and even deadly damage to the animal. The larvae can infest livestock, pets, wildlife and sometimes birds.

The name “Screwworm” refers to the maggots technique for feeding as they burrow into an animal’s wound feeding as they go like a screw being driven into wood. The insect’s sharp mouth hooks cause serious damage to animal tissue.

The pest was eradicated in the United States in 1966 using sterile insect techniques, but the USDA is on alert for reintroduction of the species.

The USDA said in 2023, New World Screwworm detections exploded in Panama. The country went from just 25 cases per year to more than 6,500 cases.

Since 2023, the pest has been found in Costa Rica, Nicaragua, Honduras, Guatemala, Belize, El Salvador, and southern Mexico, far north of the biological barrier researchers had established for the insect.

In February, the USDA announced that it was shifting its sterile fly dispersal efforts to Mexico, the northernmost point of the outbreak.

Despite eradicating the Screwworm in the 60s, Texas experienced an outbreak in 1976, which infected nearly 1.5 million head of cattle and over 300,000 sheep and goats. Texas ended up with more than $132 million worth of livestock losses that year.

Some symptoms of a Screwworm outbreak in animals include: irritated behavior, head shaking, the smell of decay, evidence of fly strike, and the presence of maggots in a wound.