Screwworm Fly: US Threat & Prevention
- A resurgence of the New World screwworm,a parasite known for consuming living flesh,is raising alarms in the U.S.cattle industry.For seven decades, the United States has waged an aerial...
- This approach successfully created a barrier at the Darién Gap between Panama and Colombia, effectively shielding North America.
- Wayne Cockrell,a Texas rancher and chair of the cattle-health committee for the Texas and Southwestern Cattle Raisers Association,expressed concern about the potential return of the screwworm to Texas.
The flesh-eating screwworm fly is rapidly approaching the U.S., threatening the cattle industry and raising serious concerns. For 70 years,the U.S. has used sterile fly releases to combat this parasite, but a breach in the barrier protecting north America now puts livestock at risk. Illegal cattle trade is fueling the screwworm’s advance,and experts warn of potential price hikes. A new sterile-fly plant within the U.S. might be necessary, and the government is being urged to take action. The current programme may lack the capacity to contain this outbreak. News directory 3 is tracking the latest developments as the USDA and Texas lawmakers race to contain the spread. Discover what’s next in the fight against this dangerous threat.
Flesh-Eating Screwworm Outbreak Threatens US Cattle Industry
Updated May 27,2025
A resurgence of the New World screwworm,a parasite known for consuming living flesh,is raising alarms in the U.S.cattle industry.For seven decades, the United States has waged an aerial war against this pest, scientifically known as C.hominivorax, which targets livestock and even humans.The U.S.Department of Agriculture (USDA) pioneered a strategy in the 1950s involving the mass production, sterilization via radiation, and aerial release of sterile screwworms to disrupt the parasite’s reproduction cycle.
This approach successfully created a barrier at the Darién Gap between Panama and Colombia, effectively shielding North America. However, in 2022, this barrier was breached. panama saw a surge in screwworm cases, and by 2024, the parasite was rapidly advancing northward.It has now reached Oaxaca and Veracruz in Mexico, prompting the U.S. to suspend live-cattle imports from Mexico.
Wayne Cockrell,a Texas rancher and chair of the cattle-health committee for the Texas and Southwestern Cattle Raisers Association,expressed concern about the potential return of the screwworm to Texas. He believes the current sterile-fly programme lacks the capacity to contain the outbreak.
“There’s a sense of dread on my part now,” cockrell said.
Cockrell noted that the U.S. cattle industry is ill-prepared for a screwworm resurgence. He cited factors such as the unavailability of certain treatments, reduced ranch staffing, and common practices like branding that leave animals vulnerable. The screwworm outbreak could further inflate already high beef prices.
The screwworm’s advance accelerated in 2024 due to illegal cattle trade,according to Jeremy Radachowsky of the Wildlife Conservation Society. Smuggled cattle transported the parasite through Central America, bypassing natural barriers.
A U.S. official familiar with the situation, who requested anonymity, said complacency resulting from decades of prosperous eradication efforts contributed to the slow initial response. The official emphasized the importance of inspections, timely reporting, and cattle movement restrictions.
Scientists have explored advanced control methods, including genetic engineering. Max Scott, an entomologist at North Carolina State university, researched a male-onyl strain and gene drives, but USDA funding for his work ended. He is now collaborating with scientists in Uruguay on gene-drive technology.
What’s next
The Texas and Southwestern cattle Raisers association is urging the USDA to construct a new sterile-fly plant in the U.S. to bolster eradication efforts. While the USDA says it is indeed working with Mexico and will reevaluate production capacity if needed, Texas lawmakers have introduced the STOP Screwworms Act to expedite the construction of a new facility.