New World screwworm outbreak returns to Texas, spreads to New Mexico

The New World screwworm, a flesh‑eating fly eradicated from the United States in the 1960s, has re‑appeared in the southern U.S. with 33 confirmed animal infections reported in Texas and New Mexico since early June. The first case was identified on June 3 in a calf from Zavala County, Texas, and subsequent cases have involved cattle, goats and a pet dog.

Texas officials have declared an infested zone (Infested Zone 14) covering parts of Sutton and Schleicher counties after a dog tested positive on July 13, marking the third dog case nationwide. Nationwide, 37 cases have been confirmed, 17 of which remain active. The U.S. Department of Agriculture continues to use a sterile‑male‑fly release program, but Texas Agriculture Commissioner Sid Miller has criticized the strategy as insufficient and called for additional insecticide‑treated traps.

State leaders warn that an unchecked outbreak could cost Texas ranchers up to $1.8 billion, and Canada has already banned livestock that passed through the affected areas. Federal officials maintain that the food supply is safe because visibly ill animals are removed before slaughter.