The U.S. Department of Agriculture (USDA) has confirmed the detection of New World Screwworm (NWS) in South Texas.
USDA Says Case Of New World Screwworm Possibly Detected In Texas
“As expected, @USDA_APHIS confirmed the detection of a New World Screwworm (NWS) fly in a 3 week old bovine in Zavala County, Texas. @USDA and Texas Animal Health @TAHC officials are taking immediate action to contain and eradicate NWS from the area,” Agriculture Secretary Brooke Rollins said.
As expected, @USDA_APHIS confirmed the detection of a New World Screwworm (NWS) fly in a 3 week old bovine in Zavala County, Texas. @USDA and Texas Animal Health @TAHC officials are taking immediate action to contain and eradicate NWS from the area.
For more… https://t.co/GJkUJl0XEI
— Secretary Brooke Rollins (@SecRollins) June 4, 2026
More from the USDA:
The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the detection of a New World screwworm (NWS) in a bovine in Zavala County, Texas. NWS is a serious pest that affects livestock, pets, wildlife, and less commonly, people and birds. NWS larvae (maggots) burrow into the flesh of living animals, causing serious damage to livestock and economic losses.
The affected animal is a 3-week-old calf and larvae were identified in its umbilical area. To date, there have been no further detections.
“All models showed New World Screwworm entering the country in 2025; however, thanks to the hard work across the entire Trump administration and our industry, state, and local partners, we were able to buy time for this moment. Protecting our livestock industry is a national security issue of the utmost importance, and USDA is wasting no time in taking action,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “USDA invested heavily in the tools needed to eliminate NWS ever since cases started increasing in Central America and Mexico. The United States has defeated this pest before, and we will do it again.”
USDA and Texas officials are taking immediate action to contain and eradicate NWS from the United States, following the strategies and actions outlined in the NWS Response Playbook (884.59 KB). This includes:
- Forming a unified Incident Command Team with the Texas Animal Health Commission and deploying response personnel to the area;
- Establishing a 20 km infested zone around the detection and implementing quarantines, movement controls, and surveillance in this area;
- Expediting targeted release of sterile NWS flies (423.58 KB) by immediately deploying ground release chambers in the area, in addition to the 4 million sterile flies per week already being released aerially in the area;
- Increasing trapping for NWS flies along the border and just outside of the dispersal area;
- Implementing NWS surveillance and management strategies in wildlife; and
- Conducting targeted outreach in the local area.
“This evening, I hosted a call with Texas media alongside @USDA Under Secretary Dudley Hoskins and Texas animal health officials to provide an update on the confirmed detection of New World Screwworm (NWS) in South Texas and outline our immediate response efforts. We briefed reporters on the aggressive actions we are taking right now in close partnership with state authorities to contain and eradicate the pest and reinforced the fact our food supply remains 100% safe,” Rollins said on Wednesday.
“We are urging producers and animal owners to follow movement restrictions and treatment guidance provided by @TAHC. USDA will continue providing regular updates as we work closely with state partners, industry stakeholders, and producers to stop the spread and protect American agriculture,” she added.
This evening, I hosted a call with Texas media alongside @USDA Under Secretary Dudley Hoskins and Texas animal health officials to provide an update on the confirmed detection of New World Screwworm (NWS) in South Texas and outline our immediate response efforts.
We briefed… pic.twitter.com/VI16BlRXYW
— Secretary Brooke Rollins (@SecRollins) June 4, 2026
NBC News shared further:
The parasite does not pose a food safety threat, but a wider outbreak could still cost the livestock industry billions of dollars and put additional pressure on beef prices that are already at record highs.
The case is the first confirmed detection of New World screwworm in Texas since 1966 and is the only confirmed case identified in the country so far, Rollins said.
It follows months of warnings from U.S. and Texas agriculture officials and cattle industry leaders, as the pest steadily moved north through Mexico toward the American border.
“For months, the screwworm has advanced rapidly through Mexico in spite of the USDA’s existing game plan,” Texas Agriculture Commissioner Sid Miller said Wednesday, adding that “instead of using every available tool, USDA moved too slowly and relied solely on a partial solution that takes years to fully implement.”
Miller has also called on President Donald Trump to take direct control of the government’s response and “throw every available federal resource at this threat before it becomes a full-blown agricultural disaster.”
The primary weapon against screwworm is a decades-old technique that has eliminated the parasite from the U.S. in the past — releasing sterilized male flies into affected areas. Since female flies generally mate only once, those that pair with sterile males are unable to produce offspring.