A case of New World screwworm has been confirmed in Zavala County, Texas, marking the first detection of the flesh-eating pest in the state since 1966.
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service confirmed the presence of the parasite in a three-week-old calf in La Pryor, Texas, roughly 30 miles from the U.S.-Mexico border.
Larvae were identified in the calf’s umbilical area, consistent with the pest’s known behavior of burrowing into wounds of living warm-blooded animals.
The detection follows months of warnings from U.S. and Texas agriculture officials as the pest moved steadily northward through Mexico toward the American border.
A USDA estimate warns that a screwworm outbreak could inflict $1.8 billion in damage to Texas’ economy alone, with broader implications for already record-high beef prices nationwide.
USDA Secretary Brooke Rollins said during a briefing: “If we all work together and follow the animal treatment protocols and movement restriction guidance, there is no reason to believe that this incursion will result in an establishment of the pest in our country.”
Rollins testified before the House Agriculture Committee that the agency expects to contain the situation, stating: “We do not believe this will be an infestation. We’ll be able to isolate each case.”
She added: “We’ve got the teams on the ground ready to go,” as federal personnel established a 20-kilometer infested zone with quarantines, movement controls, and intensified surveillance.
The USDA has also expedited the targeted release of sterile flies, a proven method used to overwhelm fertile fly populations and limit the parasite’s spread.
Rollins separately attributed the pest’s northward movement toward the border to “the open-border policies of the last administration and the resulting illicit cattle movement” in a social media post.
Texas Agriculture Commissioner Sid Miller offered a sharply different assessment, criticizing the federal government’s response as “slow, bureaucratic, and incomplete” in a press release issued shortly before the case was confirmed.
The USDA shut down the southern border to live animal imports in May 2025, cutting off cattle imports from Mexico and tightening supply conditions for Texas ranchers.
The federal government has invested $100 million into research, traps, and mounted patrol officers known as tick riders stationed at the border to monitor and intercept the pest.
When the screwworm first began spreading from Central America into Mexico, only one sterile fly production facility existed, located in Panama, creating a significant capacity constraint in the eradication effort.
Since then, U.S. officials have supported the launch of a second facility in Metapa, Mexico, expected to open this month, while a third facility is under construction in Edinburg, Texas, slated to open in fall 2027.
Human cases of screwworm infection are rare but can be fatal, though the U.S. food supply is not at risk, as the parasite does not infest meat, fruits, vegetables, or other food products.
