This week, Drovers’ Angie Stump Denton and the AgDay team have boots on the ground in South Texas, chronicling the resilience of cattle producers and the industrywide effort to contain New World screwworm. Follow along for the stories of those most impacted, market reaction and the critical steps being taken to safeguard the U.S. livestock industry.
While checking a group of heifers, Robbie Graff, manager of Rock Creek Ranch near La Pryor, Texas, spotted a 3-day-old calf with an abnormal navel. “I noticed something wrong around its navel; it was kind of pink, bloody and that gave us the indication that something wasn’t right,” he recalls.
Graff’s quick instincts and willingness to take action led to the calf being identified as the first confirmed case of New World screwworm (NWS) in the U.S. since the pest was declared eradicated in 1966.
Ground Zero Protocol: Why Concrete Surfaces Matter
That initial visual check triggered the extensive response currently unfolding in South Texas, positioning the ranch as ground zero in the renewed U.S. fight against NWS. Rather than hoping the calf’s navel would clear up on its own, Graff and his team acted immediately to contain and confirm the threat, implementing a rigorous protocol.
After catching the calf, Graff sprayed the navel area with Catron, which does not kill the larvae, and squeezed the site to reveal the infestation. To collect a sample, the team moved the calf to a concrete surface to ensure no larvae fell onto the soil — a critical step in preventing the fly’s life cycle from continuing.
They removed approximately 40 larvae from the wound, placing 20 in a syringe for veterinary testing. The remaining larvae were placed in a coffee can and destroyed with gasoline.
The calf was then treated with:
- Wound Kote (a topical treatment applied to the wound)
- Dectomax (injectable)
- LA 300 (Noromycin, an injectable antibiotic)
- Penicillin (injectable antibiotic)
- StandGuard fly control (topical)
- Farnam Wonder Dust Powder (topical)
Graff then took the syringe to his local veterinarian to verify his suspicions. From there, Texas Animal Health Commission (TAHC) officials picked up the sample and shipped it to USDA’s National Veterinary Services Laboratories in Ames, lowa, where it was officially confirmed as NWS.
“In the back of my mind, I thought it was New World screwworm,” he recalls. “I was just praying it wasn’t.”
Thanks to the early detection by Graff and his team, the calf’s wound has fully healed. His herd is now better protected through the implementation of strict prevention protocols and the strategic release of sterile flies.
Treat Fast, Then Focus on the Herd
Following the initial discovery, Graff and his team shifted their focus from the single case to mitigating risk across the entire herd.
“We have like 400 head in the area, so during the next two days we gathered everything and everyone got revaccinated with Dectomax,” he explains.
The team also applied Cydectin Pour-On and StandGuard fly control. This combination of swift individual treatment and rapid herd-wide management is exactly the response officials advocate for to effectively contain the pest. Fortunately, Graff and his team have not identified any additional cases since the initial detection.
Get Your Eyes On Your Cattle
For Graff, early detection is a matter of diligence rather than luck.
“I think it’s very important to be checking your cattle at least every other day,” he stresses. “If you’re not hands-on, have someone there to at least be able to put their eyes on the cattle. If you can, that’s what needs to be done.”
This vigilance is the core of his advice to fellow ranchers: If something appears unusual, act immediately.
“I would just say, get it to your local vet or animal health professional as soon as you can,” he says.
Don’t Be Afraid to Report A Suspected Case of NWS
While being the first confirmed case in Texas might rattle some, Graff remained focused on the task at hand rather than the publicity.
“I didn’t really think about it that way,” he says of the discovery. “We just kind of took care of business, and so here we are today. Hopefully, it’s gone.”
He credits USDA and TAHC for their efficient and supportive response.
“They’ve been very, very good. I mean, they were very prompt, and they’ve been very polite, and we hadn’t any problem, really,” he explains.
The response in his region includes sterile fly releases via aircraft and trucks — a strategy Graff recalls from the eradication efforts of the 1970s. “They started dropping flies on Wednesday night and Friday,” he explains. “They are still dropping flies in our area and surrounding area.” This emphasizes the importance of reporting suspected cases; early notification is the primary factor in how quickly sterile flies can be deployed to contain an outbreak.
How to Collect and Submit a Screwworm Sample
Since the initial confirmation, Graff says NWS test kits have been distributed to producers and area veterinarians. The TAHC website provides detailed instructions for proper sample collection and submission.
For producers who suspect an infestation, Graff suggests contacting a local veterinarian or TAHC to examine the animal and collect the sample. To expedite the process and reduce transit time to Iowa, samples are now being tested in Texas. USDA has established mobile testing units in South Texas and expanded testing capabilities at the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville.
No Food Safety Crisis — But a Serious Management Issue
To both consumers and cattlemen, Graff emphasizes this is a management and surveillance challenge rather than a food safety crisis.
“As far as our food safety, there’s really no food safety issues,” he says. “That animal is going to be quarantined for the entirety of the infection until it’s healed. It’s not like that animal is going to give it to the other animal, unless they’re infected by the fly.”
Because NWS is transmitted by flies rather than direct animal-to-animal contact, rapid detection and reporting are vital to containment.
“The main thing is just to detect it quickly because the more days it goes on, that animal doesn’t have very much chance of survival,” he explains.
‘We’ve Already Eradicated It Once’
Graff’s perspective is shaped by childhood memories of the pest and the tools used to fight it decades ago, from thick wound “paint” to the early sterile fly programs.
“There used to be a purple, it was either purple or black, [medicine], and it was kind of like putting your spoon in honey; it was really thick, and they would dab it on the wound and it would kill the worms,” he remembers.
Despite Rock Creek Ranch being confirmed as ground zero, Graff remains confident in the response.
“I guess the saving grace is we’ve already eradicated it once, so it’s not near as scary as it was back then,” he says. “If the flies are distributed and we get the other plants built and we get enough flies — I’m not worried at all.”
His message to fellow ranchers is simple: Monitor livestock closely, report findings immediately and trust the established eradication tools will work.
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