New World Screwworm Returns to U.S. Cattle: A Deep-Dive

On June 3 2026 the USDA confirmed a New World screwworm (Cochliomyia hominivorax) infestation in a Texas calf, the first domestic case in six decades. Within days a second calf, a goat in Gillespie County, and a dog in Lea County, New Mexico were added, bringing the total to six confirmed cases across Texas and New Mexico.

Associated Press

The parasite was eradicated from the United States by the 1960s through a sterile-fly program pioneered by entomologists Edward F. Knipling and Raymond Bushland. Since 2023 the fly has re-established in Panama, then moved north through Mexico and Central America, aided by illegal cattle trafficking that bypasses health screenings.

CNN

• June 3 2026 – First Texas calf case reported.

Gizmodo

• June 4 2026 – Second calf case detected 5.6 mi from the first.

Ames USDA team in Kerrville to help combat New World Screwworm outbreak

• June 8 2026 – USDA confirms two additional Texas cases and reclassifies the dog case as New Mexico.

Ames USDA team in Kerrville to help combat New World Screwworm outbreak

• June 9 2026 – USDA announces a 12-mile quarantine zone and expands sterile-fly releases.

Associated Press

• July 2025 – USDA closes southern border ports to Mexican livestock (later reopened May 2025).

CNN

• Confirmed cases: 5 livestock (4 calves, 1 goat) + 1 dog.

NewsNation

• Economic forecasts: potential $1.8 billion in Texas alone; Federal Reserve Bank of Dallas estimates up to $3 billion across the Southwest.

NewsNation

• USDA has invested $1.3 billion since 2025, plans a $750 million fly-production plant in Texas, and aims to release 500 million sterile flies weekly after the plant becomes operational (Nov 2027).

CNN

USDA Undersecretary Scott Hutchins said the Screwworm Adult Suppression System (SWASS) poses environmental risks and would undermine sterile-fly releases. Secretary of Agriculture Brooke Rollins framed the CDC activation as “one more step in the right direction” and defended the 2025 border closure, citing its role in delaying spread. Mexico’s agriculture ministry criticized the closure, while President Claudia Sheinbaum’s office declined comment.

CNN

Texas Agriculture Commissioner Sid Miller accused the USDA of “moving too slowly” and called for immediate deployment of SWASS, labeling the current approach “insanity, doing the same thing over and over and expecting different results.” Miller also urged former President Donald Trump to intervene.

CNN

Fidel Gutíerrez, a Chiapas farmer, reported calf losses of over $1,000 each due to screwworm. Texas rancher Susan Storey recalled childhood outbreaks and expressed distrust of federal response, while other ranchers praised local USDA teams for rapid quarantine enforcement.

UsNews and World Report

Sources differ on the total case count (five vs. six) and on the effectiveness of SWASS, which USDA officials deem “no longer viable” while Miller insists it works. The USDA’s border-closure impact is contested: Rollins claims it helped, Sheinbaum disputes the benefit.

CNN

• “Every cow that is being moved illegally has the potential to carry a screwworm and other diseases,” — Jeremy Radachowsky, Wildlife Conservation Society

CNN

• “It’s insanity, doing the same thing over and over and expecting different results,” — Sid Miller, Texas Agriculture Commissioner

NewsNation

• “The CDC is just one more step in the right direction that allows us to deploy more resources at the federal level,” — Brooke Rollins, U.S. Secretary of Agriculture

The Hill

• “Sterile flies are the well-established solution to the spread of the New World screwworm,” — Greg Abbott, Governor of Texas

Governor Abbott, Secretary Rollins Update Texans On Screwworm Response At Kerrville Lab

• “We are working closely with our partners in New Mexico, Texas, and across the region to ensure we identify, contain, and respond to any potential cases as swiftly as possible,” — Dudley Hoskins, USDA Under Secretary

Gizmodo

If unchecked, the fly could inflict billions of dollars in livestock losses, strain an already tight beef supply, and elevate consumer prices. Wildlife such as white-tailed deer are also at risk, and the parasite’s rapid tissue damage poses animal-welfare concerns.

CNN

The Texas sterile-fly facility is slated to begin production in November 2027, while USDA expands weekly releases and border surveillance. State and federal agencies will continue quarantine enforcement, and Colorado has issued an emergency rule to block animal movement from infected zones. Ongoing monitoring and rapid reporting remain critical to preventing a broader re-establishment of the screwworm in the United States.

Governor Abbott, Secretary Rollins Update Texans On Screwworm Response At Kerrville Lab