For the first time in decades, Texas is once again battling one of the most feared livestock parasites in North American history. The New World screwworm, a flesh-eating fly larva that was eradicated from the United States in the 1960s, has now been confirmed in multiple Texas counties, triggering emergency action from state and federal officials.
As of June 8, 2026, Texas has confirmed four cases of New World screwworm infestations. The latest detections include a calf in La Salle County and a dog in Andrews County. These new cases follow earlier infections discovered in Zavala County, bringing the total number of confirmed cases to four.
What Is the New World Screwworm?
Unlike typical maggots that feed on dead tissue, screwworm larvae feed on living flesh. Adult female flies lay eggs in open wounds, cuts, or surgical sites on warm-blooded animals. Once the eggs hatch, the larvae burrow into healthy tissue and continue feeding, creating larger wounds and potentially causing severe infections or death if left untreated.
The parasite primarily threatens cattle, horses, wildlife, and pets. In rare cases, humans can also become infected. Health officials emphasize that the parasite does not contaminate meat or pose a food safety threat, but it can devastate animal populations and agricultural operations.
Why Texas Is Concerned
Texas is home to one of the largest cattle industries in the United States, generating billions of dollars annually. Agricultural experts warn that a widespread screwworm outbreak could cause significant economic damage through livestock deaths, veterinary costs, quarantines, and trade restrictions.
The parasite has been steadily moving north through Mexico for more than a year. Federal officials have spent millions on surveillance, trapping programs, sterile fly production, and border monitoring in an effort to slow its advance. Despite those efforts, the pest has now crossed into Texas.
State and Federal Response
Governor Greg Abbott has issued a statewide disaster declaration as officials work to contain the outbreak. The U.S. Department of Agriculture and the Texas Animal Health Commission have launched an aggressive response plan that includes quarantines around infected areas, expanded surveillance, additional trapping, and aerial releases of sterile flies.
The sterile fly program has historically been one of the most successful pest eradication efforts in agricultural history. Scientists release millions of sterile male flies into affected regions. Female screwworm flies mate only once during their lifetime, meaning eggs produced after mating with sterile males never hatch. This strategy helped eliminate the parasite from the United States decades ago.
Officials report that more than 75 personnel are currently deployed in Texas, with hundreds more supporting laboratory testing, treatment distribution, air operations, and outreach efforts. Sterile fly releases continue across affected regions.
What Ranchers Are Saying
Many Texas ranchers remember stories from previous screwworm outbreaks and worry about the challenges ahead. Livestock producers must inspect animals regularly for wounds and signs of infestation. Several ranchers have expressed concern that modern labor shortages could make widespread monitoring more difficult than in past decades.
Some producers have also questioned whether the federal response moved quickly enough as the parasite advanced through Mexico. Others have called for additional resources and expanded sterile fly production capacity within Texas.
What Pet Owners Should Know
The recent Andrews County case involving a dog highlights that screwworms do not only threaten livestock. Veterinarians recommend that pet owners carefully monitor any cuts, wounds, or surgical sites, especially for animals that travel near affected regions. Signs of infestation can include worsening wounds, unusual drainage, foul odors, visible larvae, and behavioral changes caused by pain or irritation.
Early treatment is highly effective, but rapid veterinary attention is critical.
Looking Ahead
Texas officials stress that this is not yet a statewide infestation. However, the appearance of multiple cases across several counties demonstrates how serious the threat has become. Agriculture leaders remain hopeful that aggressive containment efforts, combined with proven sterile fly technology, can stop the parasite before it gains a larger foothold in the state.
For now, ranchers, veterinarians, and pet owners across Texas are being urged to remain vigilant. A pest many believed was gone forever has returned, and the battle to stop it is underway.
