New Flesh-Eating Parasite Detected Near U.S. Border

The New World Screwworm has been spotted just 90 miles from the U.S.-Mexico border, raising concerns for ranchers and consumers.

Apr. 18, 2026 at 1:20am

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A bold, highly structured abstract painting in earthy tones, resembling a massive scientific diagram with sweeping geometric arcs, concentric circles, and precise botanical spirals, conceptually representing the complex life cycle and invasive nature of the New World Screwworm parasite.An abstract visualization of the New World Screwworm, a flesh-eating parasite that is advancing closer to the U.S. border and raising concerns for ranchers and consumers.Tucson Today

A flesh-eating parasite known as the New World Screwworm has been detected about 90 miles from the U.S.-Mexico border, according to the Texas Department of Agriculture. Ranchers across southern Arizona are bracing for a potential outbreak, as the screwworm can be deadly to livestock. The University of Arizona's Veterinary Diagnostic Laboratory is working with the USDA to monitor the situation and prepare for the possibility of the pest crossing the border.

Why it matters

An outbreak of the New World Screwworm could have serious consequences for ranchers and consumers. The parasite feeds on the tissue of warm-blooded animals, including livestock, and can lead to the death of infected animals. If the screwworm spreads to cattle herds, it could significantly impact the supply of beef and drive up prices for consumers.

The details

The New World Screwworm is a species of parasitic fly that feeds on the tissue of warm-blooded animals. The University of Arizona's Veterinary Diagnostic Laboratory is one of three labs working with the USDA to monitor the situation and prepare for a potential outbreak. Ranchers are taking steps to be ready, such as building sterile fly plants and learning how to better monitor their livestock if the pest arrives.

  • The New World Screwworm has been detected about 90 miles from the U.S.-Mexico border.
  • The University of Arizona's Veterinary Diagnostic Laboratory is working with the USDA to monitor the situation.

The players

Texas Department of Agriculture

The state agency that reported the detection of the New World Screwworm near the U.S. border.

Clay Parsons

The owner of Marana Stockyards, a rancher who is concerned about the potential impact of a screwworm outbreak on his livestock.

Dr. Yan Zhang

The director of the Arizona Veterinary Diagnostic Laboratory, which is working with the USDA to monitor and respond to the threat of the New World Screwworm.

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What they’re saying

“The screwworm infestation – if it does come – is a major concern.”

— Clay Parsons, Owner, Marana Stockyards

“It can actually cause the death of animals.”

— Dr. Yan Zhang, Director, Arizona Veterinary Diagnostic Laboratory

What’s next

The USDA has fly traps set up along the border, and if any suspect flies are caught, they will be sent to the Arizona Veterinary Diagnostic Laboratory for screening. The lab is also talking with ranchers on how to be prepared for a potential outbreak.

The takeaway

The detection of the New World Screwworm near the U.S. border is a serious concern for ranchers and consumers alike. An outbreak of this flesh-eating parasite could have devastating consequences for livestock and lead to higher prices for beef and other meat products. Vigilant monitoring and proactive preparation by authorities and the agricultural community will be crucial in preventing the screwworm from crossing into the United States.