Texas Faces New Threat from Invasive Fly Species

In Kerrville, Texas, authorities have confirmed two additional cases of the New World screwworm in the state. This highlights the challenges in containing a pest that could severely impact the livestock industry, according to an announcement by the Department of Agriculture.

The screwworm is not a worm but a fly. It produces larvae that feed on live flesh rather than dead tissue. Female flies lay eggs in the open wounds of any warm-blooded animals, including livestock, wildlife, pets, and sometimes even humans.

The new cases were discovered in a calf and a dog located hundreds of miles apart in La Salle and Andrews counties, as reported by the department. This brings the total number of confirmed cases to four. Initially, the screwworm was identified last week in a three-week-old calf, and a subsequent case was found just a few miles away in another young calf.

“While we address these cases that need immediate attention and continue to sample suspected cases, we are simultaneously working to completely eradicate the pest,” stated Dudley Hoskins, the department’s assistant secretary for marketing and regulation.

Before being eliminated in the United States in the 1960s, the screwworm was an annual menace for ranchers during warm weather. Both the department and the U.S. livestock industry have been urgently trying to prevent an infestation since the pest was detected in Mexico in late 2024. It had been contained in southern Panama for decades.

The government is combating the fly by breeding sterile male flies. These sterile males mate with wild females, who mate only once in their lifetime. As a result, they produce no offspring, gradually reducing outbreaks. The department has announced plans to increase the production of sterile flies at facilities outside the United States while constructing a fly production plant in Texas.

Agriculture Secretary Brooke Rollins will receive a briefing on the infestation Monday afternoon at the Livestock Insect Research Laboratory in Kerrville, Texas.

This story was translated from English by an AP editor using generative artificial intelligence tools.