As New World screwworm edges closer to the U.S., industry leaders urge producers to shift from worry to action.
Early detection, prompt reporting and treatment — backed by coordinated surveillance along the border — will be critical to keeping this treatable pest contained. Ranches are tightening calving seasons, upgrading working facilities and revisiting parasite control plans with their veterinarians. The core message to the fight against NWS: nothing replaces “eyes on animals.”
“We’ve been preparing for the possibility of screwworms emerging back in Texas for the past year,” says Jason Sawyer, East Foundation chief science officer. “We have decided to take the attitude of preparedness. We expect we’re going to have it. How can we best manage it and best mitigate and really, how do we minimize the impact while we weather the storm?”
Sawyer participated in a panel during the The Breakthrough Symposium: NWS Preparedness, hosted by Merck Animal Health. The panelists didn’t debate whether NWS will arrive — they spoke as if it is already on the way. For producers, that means decisions must be made months in advance: adjusting breeding and calving windows to avoid peak risk, investing in better handling facilities and building a clear response plan with veterinarians. Combined with federal and state surveillance using fly traps, animal inspections and producer reports, these risk‑based steps can help ensure that when NWS appears, it is found fast, hit hard and kept from spreading.
With cattle markets at all‑time highs, panelists warn NWS must be managed in a way that protects both animal health and commerce. Movement controls, inspection and treatment protocols, and animal disease traceability are being designed to regionalize the problem — not shut the industry down.
Here are seven key takeaways from the panel discussion:
1. Prepare, Don’t Panic
New World Screwworm is a serious but manageable threat with proper planning and coordination.
“This isn’t a ‘sell the ranch and get out of business’ problem,” Sawyer summarizes. “This is a ‘let’s figure out the best way to move forward and minimize impact.’” Today’s challenge is to rebuild the “lost muscle memory” with modern tools and a risk‑based mindset. That means planning calving seasons with NWS risk in mind, enhancing parasite control without driving resistance and being ready to isolate, treat and recheck any affected animals in close coordination with veterinarians. The sooner producers start planning, the smaller and shorter the “storm” will be for everyone.
Some strategies producers should consider include:
- Get a premise ID now, if you don’t have one.
- Consider shifting calving and processing into lower‑fly windows.
- Manage wounds differently. Any break in the skin — navels, castration, dehorning, tags and tick bites — becomes a high‑risk site once NWS is in the area.
Dr. Diane Kitchen, a cattle rancher and Florida Department of Agriculture veterinarian manager, bovine and cervidae programs, suggests producers consider using a preventative or at least a protectant to the area to minimize the chance of an infestation occurring.
Sawyer, who manages ranches near the U.S.-Mexico border, explains. “We’re trying to work with the weather instead of against it and think about comprehensive parasite control strategies that can minimize that risk for newborn calves, knowing that we’re unlikely to be able to put our hands on every one of them as they hit the ground.”
2. Eyes on Animals, Surveillance is Central.
Nothing replaces routine, disciplined visual checks — especially of newborns and any animal with a wound. Kitchen says preparation starts with understanding NWS targets wounds and certain high‑risk areas. The fly’s preference is umbilical cords, she stresses.
“It can also affect certain mucus membranes,” she explains. “The corners of the eye, the genital tract. In particular, cows that are calving, they’re attracted to the same umbilical cord scent.” External wounds can be tiny, internal damage massive. “The wound itself externally may be very small,” Kitchen says. “The size of a quarter. But then when you go to treat there may be gallons of maggots within underneath.”
Producers who have dealt with the pest often describe it as a smell you’ll never forget, noting that the stench of a calf infested with New World Screwworm is often the first warning sign.
Dr. Megan Schmid, USDA-APHIS Cattle Health Center assistant director, explains there are two types of surveillance:
- Active surveillance: Fly traps along the border, border inspectors and Wildlife Services checking animals
- Passive surveillance: Producers, vets, shelters and others seeing maggots/myiasis and reporting. “The traps are helpful,” she says. ”But they’re not as sensitive as the animal inspection. So really, that’s the key part: everybody looking for the infestations in animals.”
Producers can use technology to get more “eyeballs” on cattle and keep spread to a minimum. Game cameras, virtual fencing and behavior tags can help producers find problems sooner when labor is tight.
Because these infestations can be deceptive, producers should learn to identify the specific signs of New World Screwworm, such as unusual discharge or larvae deep within living tissue.
3. Report First, Don’t Hide It.
NWS is a reportable foreign animal disease. Early reporting is critical and legally required. Officials would rather investigate 1,000 false alarms than miss one real case.
Kitchen stresses failure to report will create many more flies.
“Failure to report results in multiple generations of additional flies, which just dramatically increases the population that’s available to impact everybody,” she explains. “If you think that because you didn’t report yours, that it’s not going to be found. It will be found because it’ll be found in something else.”
She encourages producers to think about the impact on their neighbor.
If the roles were reversed, she asks, “If you hear that somebody, your neighbor, is one that didn’t report, how happy are you going to be with them?”
4. Vet Relationships Are Essential.
A veterinarian is central to preparation and treatment plan. For wound care, antibiotics, pain management and access to tools, a veterinary client–patient relationship is vital. Treatment is about parasite removal and wound management, guided by vets.
Panel members explain part of being prepared is sitting down now with your veterinarian and discussing: “If we get screwworm, what’s our plan? How often are we looking at cattle, what products are we going to use, and what do we do about movements?”
Read more about how NWS is an infestation, not an infection.
5. Wildlife Matters in This Fight.
Wildlife are a major reservoir and economic driver, and can suffer large population impacts without control. Kitchen predicts in infested areas 70% to 80% of white-tailed fawn crops could be lost.
“Our wildlife populations are both so much more abundant than they were in the 1950s and so much more valuable than they were in the 1950s,” Sawyer says. “Unfortunately, the opportunity to intervene for wildlife is much smaller. There’s really not very many strategies that are viable, and so surveillance and monitoring become really our front line of defense in terms of our wildlife populations.”
He suggests the best way to protect wildlife is aggressive control in livestock to reduce environmental burden.
6. Quarantines Are Tools, Not Punishments.
The goal is continuity of business with safeguards, not shutting down commerce. Regulators are trying to balance containment with commerce. The goal is to maintain the “speed of commerce” while using structured movement protocols to protect markets and disease-free areas.
“It’s not going to be business as usual, but it’s going to be business is still possible,” Schmid says. “The focus is: how do we allow safe movements, not restrict and stop business.”
She says the New World Screwworm Response Playbook includes guidance documents and explains the quarantine/movement framework.
Stephen Diebel, Texas beef producer and Texas & Southwestern Cattle Raisers Association president, encourages producers not to think in terms of a hard quarantine. A structured process of treatment, surveillance, inspection and certification will allow movement.
Dr. TR Lansford III, Texas Animal Health Commission assistant state veterinarian and deputy executive director, encourages producers to reference the lessons learned from fever ticks as a strategy for dealing with NWS. He notes experience with fever ticks has shaped how Texans think about area quarantines, treatment protocols and continuity of business.
7. More Tools in the Toolbox.
Panelist members summarize a holistic ectoparasite program using modern products plus strong producer education is a main NWS defense strategy.
Kitchen stress producers and veterinarians have many more tools than they did back in the ’60s and ’70s when NWS was last endemic in the U.S.
Producers can find a list of approved treatment and prevention strategies on the FDA website.
Sawyer suggests producers work with their veterinarians to plan prevention and treatment strategies. He also stresses the importance of considering resistance management.
“We don’t want to react to an emergent threat in a way that then creates problems with a persistent pest that’s already present,” he says.
Read More About How Sterile Flies are the No. 1 Tool to Fight NWS:
Doubling the Defense: USDA’s “Male-Only” Fly Breakthrough to Transform Screwworm Eradication
Border Remains Closed: Sterile Fly Production Facility Groundbreaking Next Step in Screwworm Fight
While NWS is a serious and emotionally charged threat, panelists remind producers the U.S. has pushed it back before — and can do it again.
“This pest existed here before, and it has been eradicated from the U.S. before,” Sawyer summarizes. “We know how to do it. We just have to sort of build the capacity and muscle to get it done again when we need to.”
