US invests over $1bn to combat elusive screwworm outbreak amid ongoing detection challenge

The US Department of Agriculture is dedicating more than a billion dollars to contain the return of the New World screwworm, but the insect’s elusive nature hampers efforts to identify its source and prevent a wider outbreak.

The Agriculture Department is spending more than $1bn to contain the New World screwworm’s return to the United States, but the insect remains frustratingly hard to find.

According to the New York Times, the first domestic case in decades was detected in early June in south Texas. Since then, 46 further cases have been confirmed in cattle, sheep, goats and dogs across 18 counties in Texas and New Mexico. Yet, despite more than 128 screwworm-specific traps and 8,000 exotic fruit fly traps, officials have not caught a single wild screwworm fly, leaving investigators without a clear source for the outbreak.

APHIS, the USDA’s animal health arm, says the parasite lays eggs in open wounds and can kill untreated animals as larvae burrow into flesh. The agency notes that the pest was eradicated from the US in 1966 through sterile-insect releases, but remains endemic in parts of South America and the Caribbean, which makes border monitoring and international cooperation central to the response.

State agriculture departments in Kansas and Washington have urged ranchers and veterinarians to report suspected cases quickly and to follow movement controls from affected zones. For livestock producers, the concern is not just animal welfare but the risk that an established outbreak could again impose severe costs on the cattle industry.