Industry Aligns on New World Screwworm

Facing the Threat Together: Industry Aligns on New World Screwworm

The cattle industry has faced New World screwworm (NWS) before—and won. But as experts emphasized at the recent NWS Symposium sponsored by Merck Animal Health, the threat of this devastating parasite demands renewed vigilance, stronger coordination and a proactive mindset across the entire livestock industry.

Stephen Diebel, a Texas cattle producer and president of the Texas and Southwestern Cattle Raisers Association, pointed to the magnitude of the threat, noting that New World screwworm poses a $12–$14 billion annual economic risk for the state of Texas when both livestock and wildlife are considered. That scale of loss underscores why the issue demands attention, even from producers who may feel geographically removed.

While New World screwworm does not pose a food safety concern, it is an animal health concern and its ability to devastate animal populations is well understood. Infested animals can suffer severe tissue damage, become incapacitated and, if untreated, die. The impact extends beyond cattle, affecting wildlife, companion animals and other warm-blooded species.

That broad host range makes New World screwworm a shared risk and a shared responsibility.

Image courtesy of USDA-APHIS

The adult New World screwworm fly is about the size of a common housefly (or slightly larger), with orange eyes, a metallic blue or green body, and three dark stripes. New World screwworm can be difficult to identify as it resembles other bot fly species. Confirmation of the fly identity can be determined only by a trained individual. If you see suspicious flies, contact your veterinarian immediately.

Even small wounds can serve as entry points. Experts stressed that vulnerabilities can range from something as minor as a tick bite to larger injuries. The umbilical cords of newborn calves are especially at risk. This makes routine management practices—calving, branding and processing—key moments of risk.

Additionally, New World screwworm does not respect geographic boundaries. Because it is a flying insect, it can spread across operations and regions regardless of fences or property lines. This, combined with the national movement of livestock, creates a potential pathway for rapid spread.

Dr. Diane Kitchen of the Florida Department of Agriculture emphasized that while southern climates are particularly conducive to year-round survival of NWS, the risk of outbreak is not limited to those regions. Livestock movement means that animals—and the pests that affect them—can travel far beyond their origin.

“This isn’t just a Southern issue,” was a consistent theme throughout the symposium due to the interconnected nature of the U.S. cattle industry.

The importance of early detection

Across all speakers, one principle stood out above the rest: early detection is the most powerful tool available.

Dr. T.R. Lansford III of the Texas Animal Health Commission framed it simply— “the most important thing we can put on animals for screwworms is our eyes.” Daily observation of livestock, along with awareness of wildlife and companion animals, is essential for identifying wounds and potential infestations early.

That vigilance can make the difference between a manageable situation and a widespread outbreak.

History provides a clear example. During a 2016–2017 outbreak in the Florida Keys, New World screwworm was present for multiple generations in wildlife before being officially reported. By the time authorities who could help were alerted, the parasite had already caused significant damage and mortality, particularly in wildlife populations.

Experts emphasized that producers should err on the side of caution. Even if most cases turn out not to be New World screwworm, early investigation of suspected cases is critical to protecting the broader industry.

Reporting is critical

Despite the importance of reporting, hesitation remains among some producers. Concerns about regulatory consequences or market disruptions can create reluctance.

However, symposium speakers were clear: early reporting enables rapid response. Identifying the location of an infestation allows authorities to implement control measures, including sterile insect techniques, to contain and eliminate New World screwworm before it spreads.

New World screwworm is classified as a foreign animal disease pest in the United States, and reporting suspected cases is a legal requirement for veterinarians, producers and animal caretakers.

Diebel emphasized that strong identification and reporting practices ultimately help safeguard markets. In a time of strong cattle prices, protecting regional and national market access is directly tied to how effectively the industry manages threats like NWS.

New World screwworm preparedness starts on the ranch

While government agencies and cattle industry organizations play a key role in response, preparedness begins at the ranch level to help with infestation prevention.

Producers are encouraged to take a proactive approach by evaluating their operations and identifying potential vulnerabilities. That includes:

  • Enhancing surveillance and observation routines
  • When possible, adjusting calving seasons or locations to improve monitoring
  • Minimizing injuries through facility and handling improvements
  • Strengthening relationships with veterinarians
  • Implementing or updating comprehensive ectoparasite control programs

Diebel noted that even incremental changes—such as improving surveillance or refining protocols—can make a meaningful difference.

Dr. Jason Sawyer of the East Foundation echoed that sentiment, describing preparedness as an ongoing process of evaluating risk, understanding exposure potential and identifying mitigation strategies. In many cases, it involves adapting existing animal health protocols rather than building entirely new systems.

For example, producers may consider shifting the timing of certain practices or incorporating preventive treatments earlier in the production cycle. These adjustments can help reduce the likelihood of infestation or improve response time if an outbreak occurs.

Industry-wide collaboration is essential

With recent detection in the U.S., New World screwworm response requires coordination across multiple stakeholders—producers, veterinarians, state and federal agencies, researchers and industry organizations.

Communication and information sharing are critical to ensuring that all parties understand the risk, recognize the signs and know how to respond.

Equally important is education. Producers are encouraged to share knowledge with employees, neighbors and local communities to build awareness and strengthen collective preparedness.

As speakers emphasized, the goal is not just to respond to an outbreak, but to limit its impact through early action and coordinated effort.

How New World screwworm infestations in cattle can be treated and prevented

While vigilance and preparedness remain foundational, new tools are also emerging to support the industry’s response.

At the symposium, Merck Animal Health technical services team highlighted EXZOLT® CATTLE-CA1 (fluralaner topical solution), a conditionally approved pour-on labeled for the:

  • Prevention and treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis)
  • Treatment and control of cattle fever tick (Rhipicephalus microplus)

The product represents a new class of parasiticide not previously available in the livestock industry. It has demonstrated 100% efficacy against myiasis for at least 14 days post-treatment.

As a prescription product, its use requires a veterinarian-client-patient relationship, reinforcing the importance of veterinary partnerships in overall herd health management.

While no single tool can eliminate the threat, innovations like EXZOLT CATTLE-CA1 provide producers and veterinarians with additional options to integrate into broader parasite management strategies.

The lessons shared at the NWS Symposium point to a clear path forward:

  • Stay vigilant through daily observation
  • Report early and often to enable rapid response
  • Strengthen preparedness plans at the ranch level
  • Collaborate across the industry to share information and resources
  • Leverage new tools and technologies as part of integrated management

Perhaps most importantly, the industry can draw confidence from its history. New World screwworm has been eradicated from the United States before. With coordinated effort, it can be defeated again.

Read the article here: https://www.merck-animal-health-usa.com/producers/cattle/cattle-insights/beef/breakthrough-symposium-new-world-screwworm-prevention/

 

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SCOTUS: Federal law preempts state failure-to-warn claims

SCOTUS: Federal law preempts state failure-to-warn claims

The U.S. Supreme Court’s decision that federal law preempts state law when it comes to warnings on pesticide labels may reverberate through previous court decisions involving million-dollar civil awards.

By Mary Hightower
University of Arkansas Division of Agriculture

FAYETTEVILLE, Ark. — The U.S. Supreme Court’s decision that federal law preempts state law when it comes to warnings on pesticide labels may reverberate through previous court decisions involving million-dollar civil awards.

Last week, the high court issued a ruling in Monsanto Company v. John L. Durnell. In 2019, John Durnell of St. Louis sued Monsanto claiming that two decades of glyphosate use caused him cancer. In 2023, a jury found Monsanto liable for failure to warn of potential cancer risks and awarded Durnell $1.25 million.

“Failure to warn” is about what entity decides whether a cancer warning is needed on a label. Acting under FIFRA, the Environmental Protection Agency approves pesticide labels through a process that includes scientific review and public comment. States may regulate sales and use of pesticides but may not alter labels.

The difference between state and federal authority over labels determines which law applies — state or federal — rather than which court gets to hear the case.

In its ruling, SCOTUS said that the Federal Insecticide, Fungicide, and Rodenticide Act or FIFRA expressly pre-empts a state-law failure-to-warn claim against Monsanto, because such a claim would require the company to add a cancer warning to Roundup’s label that is not part of the EPA-approved label.

“Going forward, failure to warn claims in pesticide liability lawsuits will be considered preempted by FIFRA, which means it will be virtually impossible for plaintiffs to argue those claims in court,” said Brigit Rollins, staff attorney for the National Agricultural Law Center.”

The ruling “is likely going to be a major blow to plaintiffs in Roundup cases and any other pesticide liability case because failure to warn claims have become standard for those cases and have thus far been a pretty successful argument for plaintiffs’ attorneys,” Rollins said.

As a result of the SCOTUS ruling, the Durnell case was sent back to the lower courts.

“I think it is very likely that the jury verdict will be overturned because it was based on Durnell’s claim of failure to warn,” Rollins said.

“As far as other Roundup liability cases go, I think that there are a few things we could see: Failure to warn is a central claim in these cases, but not the only claim,” she said.

“It is possible that we could see some plaintiffs drop their failure to warn claims but continue to litigate other claims to see how successful those may be,” Rollins said. “However, because failure to warn was considered the strongest claim that Roundup liability plaintiffs raised, I think that without that claim as an option, we are likely to see many plaintiffs look to settle their lawsuits.”

For more information about the NALC, visit NationalAgLawCenter.org and subscribe to receive NALC communications, including webinar announcements, the Quarterly Newsletter and The Feed.

About the National Agricultural Law Center

Created by Congress in 1987, the National Agricultural Law Center serves as the nation’s leading source of agricultural and food law research and information. The NALC works with producers, agribusinesses, state and federal policymakers, lenders, Congressional staffers, attorneys, land grant universities, students, and many others to provide objective, nonpartisan agricultural and food law research and information to the nation’s agricultural community.

The NALC is a unit of the University of Arkansas System Division of Agriculture and works in close partnership with the National Agricultural Library, a subsidiary of the USDA’s Agricultural Research Service. For information about the NALC, visit nationalaglawcenter.org. The NALC is also on X, Facebook and LinkedIn as @nataglaw. Subscribe online to receive NALC Communications, including webinar announcements, the NALC’s Quarterly Newsletter, and The Feed.

To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu. Follow us on Facebook and Instagram. To learn more about the Division of Agriculture, visit uada.edu. To learn more about ag and food research in Arkansas, visit the Arkansas Agricultural Experiment Station at aaes.uada.edu.

About the Division of Agriculture

The University of Arkansas Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land-grant education system.

The Division of Agriculture is one of 22 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on three campuses.

Pursuant to 7 CFR § 15.3, the University of Arkansas Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution.

 

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Change Modes With Your Next Grazing Plan

Change Modes With Your Next Grazing Plan

Most ranchers carry a good grazing plan in their heads, executing with a combination of intuition built on experience, an understanding of regional trends and an adaptivity to circumstances. But if you need to solve a significant problem or are ready to take aim at a new ideal like regenerative or adaptive grazing, it’s time put a proactive grazing plan on paper, Noble Research Institute Regenerative Ranching Advisor Steve Swaffar says.

“There is a heavier commitment to reach a goal you’ve written down,” he says. Writing a grazing plan on paper can feel uncomfortable, but “frankly, a good goal should make you nervous.”

For a more experienced rancher, building an ambitious grazing plan may be the slight push you need to make progress in the year ahead. For a beginning rancher or someone grazing a new piece of land, it’s an offensive plan to help navigate the unknown.

Either way, Swaffar says, “When you start putting the plan to paper, it opens all these ‘ah-ha’ moments.”

1. Start with your goals in mind

Every good grazing plan begins with a specific goal or goals.

If you worry every year about buying an unsustainable amount of hay, spend too much money on external inputs, or see an invasive species reducing your forage production, Swaffar says it’s time to meet the problem head-on by starting with a grazing goal and plan.

“These are the questions that have to stop us and make us ask, ‘How am I going to get through this?’” Swaffar says. “Well, I’ve got to sit down and make a plan, set some goals to solve the problem.” Along the way, you may uncover new opportunities as well.

Are you prepared to take advantage of an exceptionally favorable year with additional forage? Can you diversify your income with a new class or species of livestock? Could aligning your animals’ production cycle to match their environment reduce your labor requirements? What would your bottom line look like if you could sustainably produce X pounds of beef per acre?

Be realistic with these goals, Swaffar says, but remember that many good opportunities are missed due to a lack of preparation.

Finally, consider goals that will help shift your focus to create the business and life you want, Swaffar says. “Part of these goals could be, ‘My family wants to take a vacation in July.’ So where do my animals need to be to make it possible for us to be away? Build a plan from there.”

2. Take stock of where you’ll start

Once you set your goal(s), record a basic inventory of resources. You no doubt know your water sources and have a good idea of their quality and quantity, but writing it down may help address nagging, predictable problems (the well that comes up dry half the time, or the windmill that needs to be fixed every year).

“This inventory is where you can start to ask, ‘Where can I manage animals so that they’re most efficient, not walking over a mile to get to water? What opportunities do I have to create more paddocks and use this grass more efficiently?’” Swaffar says.

Next, evaluate your forage availability for the season ahead.

“If you’re a ‘trust your gut’ kind of guy, it’s still important to spot-check yourself from time to time,” Swaffar says. Use a forage stick or a clip-and- weigh method in multiple pasture locations to accurately assess your forage production.

Then, fill in dates critical to your business and the goal in mind. Calculate nutritional needs for breeding season, facility needs for calving, strengths and weaknesses in the resource inventory you have, and any other infrastructure that needs attention.

3. Plan the work, then work the plan

Once you have the critical information committed to black and white, you probably have some set dates and movements in mind or a paddock configuration that’s worked in the past. Swaffar suggests challenging your own assumptions.

If you’ve grazed one pasture from May 1 to June 15 for the past decade, try moving it to July. If you always set your paddocks up in long, skinny rectangles, try one fat square or triangles this year. Consider grazing a piece for a shorter or longer duration than you’ve ever grazed it before. Nature needs diversity to thrive, but without an intentional plan, human nature tends to fall back on ‘whatever I did last year.’

Swaffar advises making any major changes in a ‘safe-to-learn’ environment. Start small enough that if it goes wrong, it won’t be a crisis or create critical damage to land, livestock or livelihood.

“Consider making these changes in smaller, controlled areas, then observe, how did the animals and the plants react to that change? Did it get me closer to my goals?” Then, jot down some notes to establish a performance baseline.

“Some people are really numbers-driven, so they might want to see results in a soil test or see exactly how their stocking rates have changed in relation to weather patterns,” Swaffar says. “Other people monitor success by what they see – how many species of plants do I have here? How many species of invertebrates and vertebrates do I see? How are my animals behaving here? Others have 30 years of training their eye to their land, and they know from experience that they can make an accurate assessment of their land’s health.”

Take your Own Notes

Whichever category you’re in, take a moment to write down those markers and observations. Even if you don’t think you need to write it down, future generations or land managers will be grateful to inherit the historic knowledge, and you’ll be able to compare season to season and find concrete reasons to celebrate your success.

Your grazing plan may be charted in bar graphs or handwritten in bullet points. Others may use a map of proposed grazing paddocks with key dates and goals written in. Tech-driven ranchers might have an app they use or simply store the plan in their phone’s ‘notes’ feature. What matters is what gets recorded, Swaffar says.

4. Adapt to the unexpected; monitor and measure

The plan might not play out exactly as you wrote it –it’s likely not to – but the point is to increase situational awareness by identifying strengths, weaknesses, opportunities and threats so you are prepared to make thoughtful decisions in an often unpredictable business.

As the grazing season progresses, check in and adjust accordingly on a weekly, or at least bi-weekly, basis. Evaluate the state of your forage in response to actual growing conditions.

Note how the animals respond to the actions in your grazing plan and to changes to their historic grazing patterns. As Noble Ranches moved to intense rotations with more frequent livestock moves, ranch staff expressed an understandable concern for animal performance.

“There were some animals that had to be transitioned off the place – they just didn’t handle the frequent moves. That elimination was just part of the process,” Swaffar said. “But when we look at the animals that held up, our ranch staff have been quite impressed. Our fly loads are less, they’re not walking long distance to water, so they don’t seek shade as often. Watching that animal behavior is a big way to monitor the success of your grazing plan.”

Summary

For most, the ultimate measure of a grazing plan’s success will be found in their bottom line. Each of these measurements – the soil, the forage, the animals, and your lifestyle. These culminate to ask the final questions: Am I spending less to produce the same? Are these decisions resulting in sustainable profitability?

These questions can’t often be answered in one grazing season or one year. Another reason to record goals at the start and your progress or challenges along the way.

“This grazing plan is a part of a bigger business plan, and we can’t be successful in the management of the land or the animals if we don’t treat it as a business,” Swaffar says.

By Laura Nelson

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