Screwworm Alert Issued
U.S. Health Officials Issue Alert After Flesh-Eating Screwworm Found in Texas
The New World screwworm has crossed into the United States for the first time in decades. On June 3, 2026, a private veterinarian in La Pryor, Texas, found larvae in a wound on a 3-week-old beef calf. That evening, federal labs confirmed the samples as positive for *Cochliomyia hominivorax* — the flesh-eating fly whose maggots burrow into living tissue and can kill a cow in 7 to 10 days, according to KMBC.
U.S. Agriculture Secretary Brooke Rollins told Congress the next day: "This is the only case we are tracking, and we hope containment of this case will prevent further spread. We were ready and prepared." But with a potential $1.8 billion economic hit to Texas alone on the line, not everyone shares her confidence, according to WCVB.
What the Screwworm Actually Is and Does
Despite its name, the screwworm is not a worm. It is the larval stage of a blowfly. A female fly lays up to 300 eggs in any small wound — even a tick bite or a newborn calf's navel. The eggs hatch within hours. The larvae then "screw" deeper into living flesh, eating the host alive. One female can lay up to 3,000 eggs over her 30-day lifespan, according to WMUR.
Unlike most maggots, these larvae only feed on living tissue. A mild wound can become a fatal infestation in under two weeks. The pest poses a risk to livestock, deer, feral hogs, pets, and — in rare cases — humans with open wounds. Human infection, called myiasis, is uncommon but possible, especially near infested areas, according to WAPT.
The U.S. Eradicated It Once — Then It Came Back
The U.S. declared the screwworm eradicated in 1966 after a decade-long campaign. The main weapon was the Sterile Insect Technique, or SIT. Scientists release millions of sterile male flies. When they mate with wild females — who only mate once — no offspring are produced. The population collapses. This method is still the USDA's primary tool today, according to 4029TV.
Before eradication, the pest cost the U.S. livestock industry hundreds of millions of dollars each year. A small Florida Keys outbreak in 2016 threatened the endangered Key deer but was contained by early 2017. Since 2023, the screwworm has marched steadily north through Central America. It covered roughly 1,100 miles in under two years, reaching the Texas border, according to WMTW.
Federal Response: Quarantine Zones and 8 Million Sterile Flies a Week
Texas State Veterinarian Bud Dinges immediately set up "Infested Zone 01" — a 12.4-mile radius around the La Pryor detection site. No animals may leave the zone without inspection. The USDA is now releasing 4 million sterile flies per week by ground and another 4 million by air in the affected area, according to WCVB.
Feeder cattle futures markets dropped $5 per hundredweight within hours of the June 3 confirmation. Ranchers in the region are frustrated. The USDA had suspended live cattle imports from Mexico back in November 2024 after detecting the pest near Chiapas — yet the screwworm still arrived, likely carried by wildlife or pets crossing the border, according to KMBC.
Texas Officials Clash With USDA Over Who Is to Blame
Texas Agriculture Commissioner Sid Miller is not holding back. He said: "The screwworm has advanced rapidly through Mexico in spite of the USDA's existing gameplan... the consequences of that decision are now staring us in the face." Miller wants the President to deploy the Screwworm Adult Suppression System, or SWASS — a bait-and-kill chemical tool he says the USDA has underused, according to WAPT.
The USDA counters that its surveillance systems worked exactly as designed — detecting the pest fast and triggering an immediate response. The two sides also disagree on method. SIT, the USDA's preferred approach, is slower but avoids insecticides. SWASS is faster but uses chemicals. With $1.8 billion at stake, the debate is far from academic, according to 4029TV.
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