LSU Expert Christine Navarre on the Threat of New World Screwworms

Sep 3, 2025

3 min

Christine Navarre

The New World screwworm (NWS), also known as the primary screwworm, is the larvae of the fly Cochliomyia hominivorax. Unlike the larvae (maggots) of other flies that only feed on dead tissue, the NWS feeds on live tissue. This leads to more severe and potentially deadly consequences which threatens livestock and wildlife populations.


Prior to their eradication form the United States, NWS were a major economic burden to the production of livestock, especially in the in the southwestern U.S. and Florida. The U.S. Department of Agriculture estimates that the U.S. livestock industry saves approximately $900 million a year as a result of NWS eradication. Other benefits of eradication and control are enhanced human and animal health and welfare and increased survival of endangered wild animal species.


The NWS fly was eradicated from the U.S. in 1966 with the release of sterile male flies to control the population. This status is maintained through the Panama-U.S. Commission for the Eradication and Prevention of the Cattle Borer Worm (COPEG) which releases millions of sterile flies weekly along the Panama-Colombia border to create a barrier preventing the northward spread of screwworms. Due to these efforts, it is now found primarily in tropical areas of South America and some Caribbean Islands, including Cuba.


In 2016 NWS were found in Key Deer in the Florida Keys. The source of the outbreak was never determined. Rapid recognition of the problem and response with the release of sterile flies quickly eradicated the problem but this incident illustrates the importance of remaining vigilant.


In November, NWS was detected in Mexico near the Guatemala border. The USDA Animal and Plant Health Inspection Service (APHIS) has imposed immediate import restrictions on animal commodities from Mexico. They are also intensifying efforts to prevent the northward spread of NWS by collaborating with Mexican and Central American authorities and urging livestock producers along the southern U.S. border to monitor their livestock and pets for signs of NWS. Any suspected cases should be reported immediately.

Clinical Signs

NWS can infest any warm-blooded animal including livestock, pets, wildlife, birds and occasionally humans. Common sites of infestation are any fresh or old wounds, warts, tumors, tick bites and antlers in shedding. Wounds left from management procedures, such as dehorning, branding, ear tagging, tail docking and shearing, can become infested. The eyes, nose, vulva and prepuce are also vulnerable, as well as the umbilicus in newborn mammals. Animals infested with NWS may show the following signs:


  • Presence of maggots in wounds or body openings
  • Wounds with a foul odor, bloody drainage or white/cream-colored drainage (eggs)
  • Depression, reduced appetite, weight loss
  • Isolation and/or signs of discomfort, head shaking
  • Fever and other signs of secondary infection

Diagnosis and Reporting

Maggots found on animals showing the above clinical signs should be sent to a veterinarian or veterinary diagnostic lab for identification to distinguish NWS larvae from other more common fly larvae. In Louisiana larvae can be sent to the Louisiana Animal Disease Diagnostic Laboratory (www.lsu.edu/vetmed/laddl). Larvae should be placed in 70% alcohol for submission to the diagnostic laboratory.


It is very important to immediately report any NWS infestations to the Louisiana Department of Agriculture and Forestry. A reported case will not result in herd depopulation but will allow animal health officials to take steps to help you manage your animals and prevent spread. Early detection and rapid response are critical to controlling this parasite.


Treatment

Immediate veterinary care should be sought to remove larvae and properly treat with insecticides. Wound care is also important to speed healing and prevent reinfestation.


Prevention

Treatment of NWS can be difficult, and eradication is very costly, so prevention of infestations is essential. Adult NWS flies can travel up to 12 miles to lay eggs, and eggs can be transported by animals and people traveling from infested areas. This necessitates constant vigilance to ensure that reintroduction into the U.S. does not occur.


Preventative steps include:


  • Regularly inspect livestock and pets for cuts, wounds, scabs and tick infestations.
  • Closely monitor the umbilicus of newborn livestock, vulva of females and prepuce of males.
  • Use insect repellant and wound dressings to prevent fly strike.
  • Report any unusual wildlife or bird deaths to the Louisiana Wildlife and Fisheries.
  • Pay close attention to nasal passages and eyes for signs of larvae (maggot) infestation.
  • Seek veterinary advice for immediate treatment of open wounds, including dehorning and castration sites and preventive use of topical and systemic insecticides.
  • Review biosecurity plans with the farm or ranch veterinarian.

Original article by the LSU AgCenter here

Connect with:
Christine Navarre

Christine Navarre

Professor & Extension Veterinarian, School of Animal Sciences

Dr. Navarre's clinical interests are in beef cattle preventive medicine.

Beef Cattle HealthFood-Animal WelfareVeterinaryAntimicrobial StewardshipLivestock Management and Production

You might also like...

Check out some other posts from Louisiana State University

5 min

LSU expert in social and economic issues: Rural America’s unique struggles affect how it votes

An expert in social and economic issues, Professor Slack explains the unique struggles facing rural communities—like changes in jobs, health concerns, and population shifts. In this Q&A, he clears up common misunderstandings about rural life, discusses the problems rural voters face, and explores how these issues may affect their votes in this important election. What is your area of expertise? I am a professor of sociology at LSU. My research coalesces around the areas of social stratification and social demography with an emphasis on geographic space and the rural-urban continuum as axes of difference. With my colleague Shannon Monnat (Syracuse University), I recently authored the book Rural and Small-Town America: Context, Composition, and Complexities, published by the University of California Press. What are the key socio-economic challenges facing rural voters in this election? Wow. Where to start? There are so many myths and misunderstandings about rural America. One is that “rural” is synonymous with farming. To be sure, agriculture is a vital industry in terms of sustenance and national security. But technological advances and farm consolidation—the shift from many smaller farms to fewer larger farms—means most rural Americans don’t have direct economic ties to agriculture anymore. The two largest sectors of employment in rural America today are services and manufacturing, respectively. A concern regarding the service sector is that it produces jobs that vary greatly in quality depending on people’s educational level; good professional jobs for the more educated and lower quality jobs—low wages, low hours, and few to any fringe benefits—for less educated folks. Those good professional jobs tend to be concentrated in urban areas (the emergence of remote work may reshape this in the future). Manufacturing employment, which has historically been the “good jobs” sector for less educated people, has been in steady decline in terms of its share of jobs for the past 50 years. While people sometimes think of plant and factory work as urban, it has provided a larger share of jobs and earnings in rural America for decades. Deindustrialization is causing real pain in rural America: it is one thing for a plant to shut down in a large and diversified metropolis, but quite another when it is the lone “good jobs” employer in town. Other big issues are the challenges posed by population aging and youth out-migration in rural America, as well as increasing racial and ethnic diversity. Another is the factors underlying the “rural mortality penalty”—that rural America has higher death rates and lower life expectancy than urban America. These are all pressing issues. What role will rural voters play in this close presidential race, and what may sway their vote? Rural voters will play a key role in this election, assuming the margins end up being as close as they have been in the last two presidential cycles. A persuasive working-class message and a sense that rural people and places are seen—that they aren’t just “flyover country”—will help. Given that the two leading candidates hail from New York City and San Francisco, both picked running mates with a rural and small-town backstory as a nod to that constituency. All of that said, the power of the rural vote should not be overstated. The contemporary U.S. is mainly an urban society, so the winning candidate will ultimately pull most of their votes from cities and suburbs. Can you discuss any recent research on how rural voting patterns have evolved over the last few election cycles? The short answer is that the rural vote has been steadily trending Republican for decades. The last presidential election in which voters in metropolitan and nonmetropolitan counties were essentially equal regarding party preferences was in 1976 when Jimmy Carter was elected. Since that time, the percentage of nonmetro votes for the Republican candidate has trended steadily upward. In 2020, roughly two-thirds of the nonmetro vote went to Donald Trump, more than 20 points higher than in metro counties. That said, rural voters are not a monolith. The flip side of the 2020 numbers above is that roughly 1 in 3 voters in nonmetro counties cast their ballot in the other direction. And rural places with majority Black, Latino, and Indigenous populations often vote in the Democratic column. Moreover, you have political legacies particular to certain places that matter—like the left-leaning Farmer-Labor Party in Minnesota (today the Democratic-Farmer-Labor Party or DFL) or the rural state of Vermont electing a socialist to the U.S. Senate (Bernie Sanders). So, there are notable deviations from the aggregate trend. “ The problems and prospects facing rural America in the 21st century matter for this nation. Personally, I would love to see a less ideological and more pragmatic politics emerge that puts that in focus. ” How do political campaigns target rural voters, and how effective do you think these strategies are? This is a bit outside my area of expertise, and I want to stay in my lane. But I will raise two issues. One is what the political scientist Katherine Cramer has called “rural consciousness”: a belief that rural areas are ignored by policymakers, that rural areas do not get their fair share of resources, and that rural folks have distinct values and lifestyles that are misunderstood and disrespected by city folks. The message from some quarters that rural people vote “against their own self-interest” or vote “the wrong way,” essentially that they are rubes, feeds into this. The other issue is that much of rural America is a local “news desert.” That is, there simply are no sources of comprehensive and credible local news. So, people rely on cable TV news or—if they have access to broadband—the internet. The result is that all news becomes national, even when those issues may have little bearing on local life. It used to be said that “all politics is local,” but in today’s media environment, that is increasingly untrue. Is there anything else you want to add? I would just emphasize that common myths and misunderstandings about rural America run deep. Rural America is not a paragon of stability, social and economic change abounds. And rural America is not a monolith, it is socially and regionally diverse. The problems and prospects facing rural America in the 21st century matter for this nation. Personally, I would love to see a less ideological and more pragmatic politics emerge that puts that in focus. Link to original article here. 

3 min

LSU, FUEL, Syngenta Partner to Develop Low-cost Digital Twins for Chemical Processing Facilities

Derick Ostrenko and Jason Jamerson, faculty in the LSU College of Art & Design, along with engineering advisor David Ben Spry, are pioneering a new approach to industrial innovation using digital twins. The effort is supported by a $217,403 use-inspired research and development (UIRD) award from Future Use of Energy in Louisiana (FUEL). Digital twins are highly detailed, virtual replicas of physical assets. The technology is used in engineering to enhance efficiency, safety, and training; however, their creation often requires costly specialized hardware, proprietary software, and engineering-intensive workflows. “This initiative not only advances digital twin technology but also highlights the interdisciplinary power of design and engineering,” FUEL UIRD Director Ashwith Chilvery said. “By applying creative tools in an industrial setting, we’re demonstrating new ways to lower costs and expand access to advanced digital infrastructure.” The collaborative effort between LSU, FUEL, and Syngenta aims to reduce costs by applying techniques more commonly used in the entertainment industry, leveraging free and open-source software and consumer-grade hardware, such as gaming PCs and digital cameras. Most of the work will be conducted by digital art students skilled in 3D modeling and video game production, offering a cost-effective alternative to traditional engineering services. “3D artists and game developers bring both technical expertise and creative vision that can add significant value when paired with traditional engineering approaches,” Spry said. “We’re eager to demonstrate how this talent pool can help accelerate digital transformation in industry.” “Working with an innovative company like Syngenta to advance digital twins for chemical manufacturing is an outstanding opportunity for our researchers and students, and we’re proud of the techniques and talent we’ve developed at LSU. FUEL’s support of digital twin development for the energy and chemical sectors helps build this technology and unique artistry in Louisiana, for our industries, and for the rest of the nation.” - Greg Trahan, LSU Assistant Vice President of Strategic Research Partnerships In addition to producing a high-fidelity digital twin of a process unit within an active chemical manufacturing facility, the project will deliver a virtual reality application that allows immersive interaction with the 3D model. Future extensions may include augmented reality overlays of physical equipment or integration of live process data for real-time monitoring and troubleshooting. The ultimate outcome of the project is a validated workflow that reduces the cost of producing digital twins by a factor of at least five compared to conventional engineering methods. This breakthrough has the potential to redefine digital infrastructure for the chemical processing industry, making it more accessible, scalable, and adaptable to future needs. Learn more about LSU's digital twin work with Syngenta as well as NASA: About FUEL Future Use of Energy in Louisiana (FUEL) positions the state as a global energy innovation leader through high-impact technology development and innovation that supports the energy industry in lowering carbon emissions. FUEL brings together a growing team of universities, community and technical colleges, state agencies and industry and capital partners led by LSU. With the potential to receive up to $160 million in funding from the U.S. National Science Foundation through the NSF Regional Innovation Engines program and an additional $67.5 million from Louisiana Economic Development, FUEL will advance our nation’s capacity for energy innovation through use-inspired research and development, workforce development, and technology commercialization. For more information, visit fuelouisiana.org. About Syngenta Syngenta Crop Protection is a global leader in agricultural innovation. It is focused on empowering farmers to make the transformation required to feed the world’s population while protecting our planet. Its bold scientific discoveries deliver better benefits for farmers and society on a bigger scale than ever before. Syngenta CP offers a leading portfolio of crop protection technologies and solutions that support farmers to grow healthier plants with higher yields. Its 17,700 employees are helping to transform agriculture in more than 90 countries. Syngenta Crop Protection is headquartered in Basel, Switzerland, and is part of the Syngenta Group. Read our stories and follow us on LinkedIn, Instagram & X.

2 min

Largest Cohort in LSU History: Six Distinguished Faculty Members Named Boyd Professors

Named in honor of brothers Thomas and David Boyd, early presidents and faculty members of LSU, the Boyd Professorship recognizes faculty who bring honor and prestige to LSU through their national and, as appropriate, international recognition for outstanding achievements. Before today, only 79 faculty members from all of LSU’s campuses have ever achieved this distinguished rank. The newest cohort of Boyd Professors represent a wide variety of disciplines and hail from three of LSU’s eight campuses: LSU A&M, Pennington Biomedical Research Center, and LSU Shreveport. This group includes LSU Shreveport’s first-ever Boyd Professor, a landmark achievement for the campus and a testament to its academic distinction. As the largest group of Boyd Professors ever named at one time, this cohort underscores LSU’s rising reputation for research excellence across all of its campuses. “This is a moment of real pride for LSU. Naming six new Boyd Professors is not only historic in scale, it's a clear reflection of the extraordinary strength and momentum of our academic enterprise,” said Interim LSU President Matt Lee. “These scholars are advancing knowledge in ways that reach far beyond our campuses, and their work is helping to define LSU’s place on the national and global stage. I am especially proud to see LSU Shreveport represented for the first time, a milestone that reflects the growing excellence across our campuses. This achievement is a powerful reminder of our commitment to advancing scholarship and shaping the future through research, education, and service.” The newest Boyd Professors are: Mette Gaarde, Les and Dot Broussard Alumni Professor, Department of Physics and Astronomy, College of Science, LSU A&M John Maxwell Hamilton, Hopkins P. Breazeale LSU Foundation Professor, Manship School of Mass Communication, LSU A&M Steven Heymsfield, Professor of Metabolism and Body Composition, Pennington Biomedical Research Center Michael Khonsari, Dow Chemical Endowed Chair and Professor, Department of Mechanical Engineering, College of Engineering, LSU A&M Alexander Mikaberidze, Professor of History, Ruth Herring Noel Endowed Chair, College of Arts & Sciences, LSU Shreveport R. Kelley Pace, Professor, Department of Finance, E. J. Ourso College of Business, LSU A&M Nominations for the Boyd Professorship are initiated in the college, routed for review and support at the campus level, then considered by the LSU Boyd Professorship Review Committee, which seeks confidential evaluations from dozens of distinguished scholars in the candidate’s field of expertise. Once endorsed by the review committee, the nomination is forwarded to the LSU President and Board of Supervisors for consideration. With this distinction, a Boyd Professor’s compensation is elevated to reflect the stature of LSU’s most distinguished faculty, with a salary set at no less than the 95th percentile of full professors in comparable disciplines at peer public institutions across the southeastern United States. They also receive an annual stipend to further support their research and scholarly pursuits. Please join us in congratulating these faculty on this outstanding accomplishment.

View all posts