US-Mexico Border Reopens for Cattle Imports after New World Screwworm Scare

US-Mexico Border Reopens for Cattle Imports after New World Screwworm Scare

Legal Insurrection readers may recall that in May, I reported the United States had suspended the importation of live cattle, horses, and bison from Mexico through all southern border ports, due to the threat posed by the New World Screwworm (NWS), a dangerous, flesh-eating parasite.

The New World Screwworm (Cochliomyia hominivorax) is a flesh-eating parasitic fly whose larvae infest open wounds of warm-blooded animals, including livestock, wildlife, pets, and occasionally humans, causing severe tissue damage, and often death, if left untreated. The larvae burrow into living flesh using sharp mouth hooks, distinguishing them from other blowflies that feed only on dead tissue.

Now, the border is back open for cattle imports.

U.S. Agriculture Secretary Brooke Rollins said via X that “key progress” had been made. She noted that more than 100 million sterile flies were being dispersed weekly and there had been no northward spread in eight weeks.

The U.S. restricted Mexican cattle shipments in late November following the detection of the pest, but lifted the ban in February after protocols were put in place to evaluate the animals prior to entry into the country. But after an “unacceptable northward advancement” of the screwworm, the U.S. Department of Agriculture said in a statement it was suspending them again in May.

Mexico Agriculture and Rural Development Secretary Julio Berdegué said he participated in a virtual meeting with Rollins Monday and that the border opening would begin July 7.

As I noted in my piece, our country had mostly eradicated these pests in the 1960s and 1970s by breeding sterilized males of the species and dispersing them from planes to mate with wild, female flies. While Panama has supplies of these sterile insects that are being used along those same lines, there are now plans to open up “fly factories” in both Texas and Mexico.

…[T]oday only one facility in Panama breeds sterilized New World screwworms for dispersal, and hundreds of millions more sterile flies are needed to slow the outbreak, according to a June 17 letter from 80 US lawmakers.

The next day, the US Department of Agriculture announced plans to open a “fly factory” in a yet to be determined town near the Texas-Mexico border. But the process of defeating the screwworm may not be quick — or inexpensive.

It turns out that the U.S. had fly factories in both Florida and Texas. These facilities were closed years ago, after as the pest was successfully eradicated.

The USDA expects a new screwworm fly factory to be up and running in southern Mexico by July 2026. It plans to open a fly distribution center in southern Texas by the end of the year so that it can import and distribute flies from Panama if necessary.

…The Panama fly factory can breed up to 117 million a week, but the USDA wants the capacity to breed at least 400 million a week. It plans to spend $8.5 million on the Texas site and $21 million to convert a facility in southern Mexico for breeding sterile fruit flies into one for screwworm flies.

I am glad to see the Trump administration has learned some valuable lessons about shortening supply chains, especially for items related to bio- and food-security.

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