The U.S. Department of Agriculture has released more than 1 billion sterile flies to fight the flesh-eating New World screwworm, yet Agriculture Secretary Brooke Rollins says the pest has not been eradicated. Rollins said USDA is currently releasing about 100 million sterile flies per week in Texas and Mexico, according to an RFD-TV report on the expanding screwworm response filed September 23 from Santa Teresa, New Mexico.

The milestone comes as the U.S. outbreak reaches 50 confirmed animal cases since June, including 48 in Texas and two in New Mexico, according to a Houston Public Media tracker updated September 21. The most recent was a horse in Grant County, New Mexico, detected September 17. Three cases were active as of September 18, according to USDA figures reported by KVIA.

Update Note: This article reports developments in the New World screwworm response since the first U.S. detection in June 2026. Latest verified figures: RFD-TV report of Secretary Rollins' remarks, September 23, 2026; case counts through September 21, 2026.

For households in South and Central Texas, the practical message has not changed. Livestock, pets, and wildlife remain at risk wherever the fly is active, and anyone who owns animals near an infested zone should keep inspecting wounds.

Scale Versus the Eradication Target

The sterile insect technique works by releasing large numbers of sterile male flies. Wild females that mate with them produce no offspring, and over successive generations the population declines. The same approach eliminated screwworm from the United States in the 1960s, and it remains USDA's primary eradication tool.

The current effort is large but short of the scale that won that fight. According to Screwworm.gov, USDA's investments will bring production to approximately 500 million sterile flies per week, the same amount used to eradicate the pest decades ago. Today's release rate of about 100 million per week is roughly one-fifth of that level, and Houston Public Media reported that USDA aims to reach the target by next summer.

USDA says its facility in Panama produces about 100 million flies weekly, a renovated plant in Metapa, Mexico, is ramping toward another 100 million, and a South Texas production facility is designed for 300 million per week. Surveillance has expanded as well. Rollins reported more than 1,800 drone flights, monitoring of more than 110,000 wild animals, and dedicated traps along the border, and she said no screwworm had been detected in monitored wildlife.

Texas Zones Begin to Lift

The first U.S. case in this outbreak was a 3-week-old calf in Zavala County, Texas, confirmed June 3, with larvae found in its umbilical area. As cases spread, the Texas Animal Health Commission set up infested zones with movement requirements for animals.

Some of those zones are now being released. On September 21, the commission released Infested Zone 11 and modified Infested Zone 04 with USDA's concurrence, following other zone releases announced September 16 and 18. Houston Public Media reported that restrictions have eased in parts of Gillespie, Kerr, Kimble, La Salle, and Webb counties. APHIS said several infested zones in Texas remain in place, and interstate and export requirements still apply in released areas.

Federal officials say the parasite's northward spread has slowed, but Rollins cautioned that the threat has not passed, pointing to Arizona and New Mexico as areas of concern. "We're not out of the woods yet," she said, according to Houston Public Media.

Ranchers, Pet Owners, and Hunters

The heaviest burden falls on livestock producers in South Texas and the Hill Country, especially those with newborn animals, since screwworm flies lay eggs in open wounds and natural body openings, including the navels of newborns. Owners inside active zones must meet inspection requirements before moving animals out.

Pet owners are affected too. A dog in Lea County, New Mexico, was among the earliest confirmed cases, and pets and service animals arriving from countries affected by screwworm must meet USDA and CDC import requirements. APHIS has also posted guidance for hunters, since deer and other wildlife can be infested.

Border trade adds another layer. Under USDA's plan for a phased reopening of southern cattle ports, the Douglas, Arizona, port reopened to cattle from Mexico on August 24, with every animal inspected for signs of screwworm. Rollins announced on September 17 that the Santa Teresa, New Mexico, port was scheduled to reopen September 24, starting with several hundred head of cattle per day. USDA has said it is also evaluating the Columbus, New Mexico, port, and that openings may be paused if it identifies increased risk in the Mexican states of Sonora or Chihuahua.

For shoppers, USDA says screwworm is not a food safety issue and that the U.S. food supply remains safe. The agency says "the current risk to animals and people in the United States is very low." The CDC reports no locally acquired human infestations in the United States, though human cases, while rare, can occur through open wounds.

Checking Animals and Reporting Wounds

Officials ask animal owners to watch for wounds that do not heal or that grow worse, wounds with maggots or a foul odor, and animals that persistently lick or bother a wound. Pay close attention to the navels of newborn animals and to ears, noses, and recent injury sites. Keeping wounds clean and covered reduces risk.

Texas owners should check the Texas Animal Health Commission zone map to see whether their location falls in an active zone and what requirements apply. Suspected cases in Texas livestock can be reported to a commission region office or to the state veterinarian on call at 1-800-550-8242. Suspected cases in Texas wildlife go to Texas Parks and Wildlife. Owners in other states should contact their state veterinarian. Fast reporting matters because each confirmed detection triggers an infested zone, targeted sterile-fly releases, and added surveillance that protect neighboring herds.

Anyone who finds larvae in a wound on their own body, especially after travel to Mexico or Central America, should seek medical care promptly.

Milestones Ahead in the Screwworm Fight

The next milestones are fly production and trade. New capacity in Mexico and South Texas is central to reaching the 500-million-per-week target, and the Santa Teresa reopening will be the largest test yet of the new import inspection protocol. USDA says port openings remain dependent on disease risk.

Case counts may keep rising as long as wild flies remain active in the region, and USDA says it will keep adjusting sterile-fly dispersal and movement controls as detections change.

USDA's response has grown substantially, and some Texas zones are reopening, but by the Secretary's own account, eradication has not been achieved. Animal owners in affected areas should keep checking for wounds and report anything suspicious quickly.

What Readers Want to Know

How many screwworm cases have been confirmed in the U.S.?

As of September 21, there were 50 confirmed animal cases since June, including 48 in Texas and two in New Mexico, according to Houston Public Media's tracker of official data.

How many sterile flies has USDA released?

Agriculture Secretary Brooke Rollins said USDA has released more than 1 billion sterile flies and is releasing about 100 million per week in Texas and Mexico.

Is screwworm eradicated?

No. Rollins said eradication has not been achieved, and several infested zones remain in place in Texas.

Is beef safe to eat?

Yes. USDA says New World screwworm is not a food safety issue and that the current risk to people in the United States is very low.

What signs should animal owners look for?

Watch for wounds that do not heal or worsen, maggots, foul odors, and animals persistently licking a wound, especially around the navels of newborn animals.

How do I report a suspected case in Texas?

Contact a Texas Animal Health Commission region office or the state veterinarian on call at 1-800-550-8242. Report wildlife cases to Texas Parks and Wildlife.

Are cattle imports from Mexico resuming?

Yes, in phases. The Douglas, Arizona, port reopened August 24, and the Santa Teresa, New Mexico, port was scheduled to reopen September 24.