Texas ramps up effort to keep Mexican flesh-eating parasite away from its cattle ranches

The first center for dispersing sterile screwworm flies from U.S. soil in decades opened Monday in Texas, part of a larger effort to keep the flesh-eating parasite they spawn from crossing the Mexican border and wreaking havoc on the American cattle industry.

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U.S. Agriculture Secretary Brooke Rollins and Texas Gov. Greg Abbott unveiled the new facility on a former Air Force base near Edinburg, Texas. It will allow the U.S. to disperse millions of sterile male New World screwworm flies bred in Mexico or Panama on both sides of the border.

The U.S. Department of Agriculture is building a new $750 million factory nearby for breeding sterile flies, but Rollins said construction on the fly factory won’t be done until the end of 2027. The USDA also is spending $21 million to convert a fruit fly breeding facility in far southern Mexico into one for breeding screwworm flies starting this summer.

The sterile male flies would mate with wild females, who mate only once in their weekslong adult lives. Their eggs, laid in open wounds or on mucous membranes, would then not hatch into the flesh-eating maggots that can infest livestock, wild mammals, household pets and even humans.

“It’s a real testament to the all hands on deck — federal state and local — the fact that we do not have the pest in our country yet,” Rollins said.

In November, the USDA opened a facility in Tampico in central Mexico for dispersing Panama-bred flies. However, it is about 330 miles (530 kilometers) south of the U.S.-Mexico border.

“We knew we needed a short-term, gap-filling solution, which is exactly what we are cutting a ribbon on today,” Abbott said.

The Mexican cattle industry has been hit hard by New World screwworm fly larvae infestations, and the U.S. has closed the border since July to imports of cattle, bison and horses.

A similar program breeding sterile male flies had largely eradicated the pest from American soil by the early 1970s, except for a limited, short-lived outbreak in the Florida Keys in 2017 and its appearance recently when officials blocked a horse being imported from Argentina into Florida until the animal was fully treated, Rollins said.

The U.S. shut down its fly factories after eliminating the pest from its soil, and sterile males have been bred since in the Western Hemisphere only at a single facility in Panama, which can produce about 117 million a week. The new fly factory in Texas would be designed to produce 300 million a week.

The USDA also announced last month that it is offering up to $100 million in grants for projects designed to improve fly breeding, create new fly traps and lures, and produce treatments for infestations.

Hanna reported from Topeka, Kansas.

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