Flesh-eating screwworms spread to third state and are attacking pets

For a genuine fright this Halloween, you can turn your gaze to the southern border, where ravenous, flesh-eating maggots are festering and have taken to eating people’s pets.

This week, the country’s New World Screwworm (NWS) infestation spread to a third state, Arizona, which joins New Mexico and Texas in being plagued by the horrifying parasites. To date, 74 animal cases have been identified in the US since the flies re-invaded the country in June.

The flies lay hundreds of eggs in wounds and moist orifices of animals, and the resulting voracious maggots feast on their victims. The maggots resemble screws and tortuously bore and twist into living flesh, causing severe, sometimes fatal wounds, before dropping to the ground to develop into adults.

Because of their ability to ravage livestock, the flies were eliminated from the country in the 1960s through aerial releases of sterile male flies, which thwart successful breeding. For years, they were held at bay using a biological barrier along the Darién Gap at the border of Panama and Colombia. But the barrier was breached in 2022, and the flies have made their way back to the US through Central America.

No one is safe

While they are largely seen as a threat to the livestock industry, they can also devastate wildlife, domestic pets, and in rarer cases, humans. According to the latest data from Mexico’s Ministry of Health, the country has confirmed 806 cases of human screwworm infestations since the flies reemerged. Nine people died from the savage maggots.