The U.S. Department of Agriculture has initiated a sterile fly release program in Texas to combat a flesh-eating screwworm outbreak affecting livestock, as confirmed by the agency on June 5, 2026.
The Outbreak and Its Impact
The screwworm infestation, first detected in Texas in early 2026, has spread to at least 12 counties, according to the U.S. Department of Agriculture (USDA). The parasitic fly, *Cochliomyia hominivorax*, lays eggs in open wounds of mammals, leading to necrotic tissue damage and, in severe cases, death. The outbreak has prompted emergency measures, including restrictions on livestock movement and heightened surveillance in affected regions.
Initial reports indicated that over 500 animals had been confirmed positive for the infestation by mid-May 2026, though the USDA has not released updated figures as of June 6. The agency emphasized that the outbreak poses no direct risk to humans but threatens agricultural economies, particularly in the southern U.S., where cattle and sheep farming is prevalent.
Sterile Fly Program Details
The USDA’s response centers on the sterile insect technique (SIT), a method proven effective in eradicating screwworms in the 1950s and 1960s. Under this approach, male flies are irradiated to render them sterile and then released in large numbers to mate with wild females. The resulting eggs fail to hatch, gradually reducing the population.
According to a June 5 press statement, the agency has begun releasing sterile flies in a 1,200-square-mile zone in West Texas. “This targeted approach aims to suppress the infestation without harming the environment or non-target species,” the USDA said. The program is expected to last six months, with periodic evaluations to assess efficacy.
Historically, SIT eliminated screwworms from the U.S. by 1982, but the species reemerged in 2024 after being detected in Mexico. The current outbreak marks the first U.S. case since that eradication, prompting renewed reliance on the method.
Role of Canines in Surveillance
In addition to the sterile fly program, the USDA has deployed canines trained to detect screwworm infestations in livestock. These dogs, sourced from specialized units in Texas and New Mexico, are used to screen animals for signs of infection, such as lesions or odor changes associated with maggot activity.
“Dogs provide a rapid, non-invasive way to identify affected animals,” said Dr. Emily Carter, a USDA veterinary epidemiologist. “Their ability to detect early-stage infestations complements the sterile fly program by enabling quicker containment.”
The use of detection dogs is not new; similar methods were employed during the 2024 outbreaks in Mexico. However, the current deployment represents the first large-scale integration of canine units into U.S. screwworm response efforts.
Challenges and Timeline
The USDA faces logistical hurdles in implementing the program, including coordinating fly releases across vast rural areas and ensuring compliance with livestock movement restrictions. Additionally, public skepticism about the safety of irradiated insects has led to local opposition in some communities.
State officials in Texas have reported mixed reactions. While farmers in affected regions generally support the measures, some ranchers argue that the program’s timeline is too slow to prevent economic losses. “We need more immediate action to protect our herds,” said a representative from the Texas Cattlemen’s Association in a June 3 interview.
The USDA has not specified a definitive end date for the sterile fly releases but stated that the program will continue until the infestation is “effectively suppressed.” Monitoring will remain in place for at least 12 months post-intervention to prevent resurgence.
Future Prospects
If successful, the current initiative could set a precedent for using SIT and canine surveillance in future outbreaks. The agency has also explored partnerships with Mexican authorities to address cross-border infestations, though no formal agreements have been announced as of June 6.
Experts note that the program’s long-term viability depends on sustained funding and public cooperation. “This is a complex, multi-year effort,” said Dr. Michael Torres, a parasitology professor at the University of Arizona. “The key will be maintaining vigilance and adapting strategies as new data emerges.”
As of June 6, no cases of the outbreak have been reported outside Texas, but the USDA has warned that the infestation could spread if control measures falter. The agency continues to collaborate with state governments and agricultural organizations to mitigate risks and ensure the program’s success.
