Additional Coverage:
The New World Screwworm (NWS), a parasitic fly known for burrowing into the flesh of livestock and other warm-blooded animals, has made its way into South Texas, raising concerns among agricultural officials and ranchers.
On June 3, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) confirmed the presence of NWS larvae in the umbilical area of a three-week-old calf in Zavala County, Texas. By June 11, six cases had been documented, underscoring the urgency of the situation.
NWS larvae pose a serious threat to livestock, pets, wildlife, and occasionally humans and birds. While the presence of screwworms does not render meat unsafe for consumption, their impact could drive beef prices even higher amid already record levels.
In response to the threat, Agriculture Secretary Brooke Rollins announced on May 11, 2025, a suspension of live cattle, horse, and bison imports through southern border ports due to the rapid northward spread of NWS from Mexico.
USDA Under Secretary Dudley Hoskins noted that models predicted the pest’s arrival in the U.S. this year, but efforts by the Trump administration, along with state and local partners, helped delay its spread. “The United States has defeated this pest before, and we will do it again,” Hoskins affirmed.
An APHIS strike team is actively working on-site in Texas, employing a combination of sterile male fly releases and livestock movement controls to contain the outbreak.
Historically, the USDA began combating NWS in the 1920s and 1930s, utilizing the Screwworm Adult Suppression System (SWASS)-a bait containing insecticides that targets adult flies before reproduction. Additionally, sterile male flies were released to prevent offspring production, leading to the successful eradication of NWS from the United States by 1966.
Despite these efforts, Texas Agriculture Commissioner Sid Miller has criticized the USDA’s current response, highlighting that the screwworm has advanced over 1,100 miles through Mexico despite billions of sterile flies being released. Miller claims he provided the SWASS bait formula to USDA officials multiple times but contends that the agency’s reliance on partial solutions has delayed an effective response. He has called on President Trump to take direct control and accelerate deployment of resources.
Meanwhile, Texas Land Commissioner Dr. Dawn Buckingham, overseeing millions of acres of state land, has pledged full support to federal and state agencies. Her office has offered access to lands for housing workers, growing sterile flies, and setting traps to aid containment efforts.
Buckingham emphasized the seriousness of the threat, noting that screwworms affect not only cattle but also wildlife, dogs, and cats. She acknowledged that while screwworms have resurfaced after being suppressed decades ago, modern mobility and trade contribute to their spread.
However, she expressed confidence in available treatments and containment strategies, stating, “We fought them before. We’ll fight them successfully again.”
As authorities mobilize to contain the New World Screwworm, vigilance and coordinated action remain critical to protecting Texas’s livestock industry and wildlife from this invasive pest.