The US plans to open a fly factory in Texas as part of its fight against a flesh-eating parasite

Winnipeg Free Press

18-06-2025

The U.S. government plans to open what amounts to a fly factory by the end of the year, announcing its intent Wednesday to breed millions of the insects in Texas near the border with Mexico as part of an effort to keep a flesh-eating parasite from infesting American cattle.
Agriculture Secretary Brooke Rollins said sterile male New World screwworm flies bred at the $8.5 million facility would be released into the wild to mate with females and prevent them from laying the eggs in wounds that become flesh-eating larva. It would be only the second facility for breeding such flies in the Western Hemisphere, joining one in Panama that had largely kept the flies from migrating further north until last year.
The fly's appearance in southern Mexico late last year has worried agriculture and cattle industry officials and veterinarians' groups, and the U.S. last month suspended imports of live cattle, horses and bison from Mexico. The U.S. Department of Agriculture also plans to spend $21 million to convert a facility for breeding fruit flies near Mexico's southernmost border with Guatemala into one for breeding sterile New World screwworm flies, but it won't be ready for 18 months.
The U.S. bred and released sterile New World screwworm flies into the wild decades ago, and it was largely banished from the country in the 1960s. Previously, it had been an annual scourge for cattle ranchers and dairy farmers, particularly in the Southeast.
'The United States has defeated NWS before, and we will do it again,' Rollins said. She held a news conference at Moore Air Base with Texas and cattle industry officials.
Mexican Agriculture Secretary Julio Berdegué said in a post Wednesday on X that Rollins' plan 'seems to us a positive step in different aspects, it will strengthen the joint Mexico-US work.'
'We trust the enthusiasm for cooperation that Secretary Rollins mentioned, and based on objective results and the reports from the USDA mission visiting us this week, we will be able to restart exports of our cattle as soon as possible,' he said.
The new Texas facility would be built at Moore Air Base, less than 20 miles (32 kilometers) from the Mexico border, and the USDA said it would also consider building a companion fly-breeding center there so that up to 300 million flies could be produced a week. The Panama facility breeds about 100 million a week, and the one in Mexico could breed as many as 100 million as well.
The USDA has said the flies have been detected as close as 700 miles (1,127 kilometers) from the U.S. border, and some U.S. agriculture and cattle industry officials have worried that if the migration isn't checked, the flies could reach the border by the end of summer. Pressure from the U.S. prompted Mexico to step up efforts to control the fly's spread.
Buck Wehrbein, a Nebraska cattle rancher and the president of the National Beef Cattlemen's Association, said Moore Air Base had a fly-breeding facility in the 1960s that helped eradicate it in the U.S.
While there are treatments for New World screwworm infestations, cattle industry officials still worry that farmers and ranchers could see huge economic losses. They, agriculture officials and scientists also said the larva can infest any mammal, including household pets, and it has occasionally been seen in humans.
'The only way to protect the American cattle herd from the devastating threat of New World screwworm is by having a sufficient supply of sterile flies to push this pest away from our border,' Wehrbein said.
Texas officials said they are grateful that the U.S. is taking the screwworm threat serious and pleased with the plans for combating it, including the new facility in Texas.
Officials in other states are watching the fly's migration as well and see having sterile male flies outnumber the non-sterile one is crucial to checking its migration.
'We have a real concern about wildlife because of their ability to cross the border unchecked somewhat, whether it's feral pigs, deer, wild cattle, whatever the case may be,' Kansas Animal Health Commissioner Justin Smith said in a recent interview. 'There's an opportunity for them to be our exposure risk.'