Screwworm Parasite Detected in South Texas

The New World screwworm fly has been detected in South Texas, posing a significant threat to the region's cattle herd ^[1].

This parasitic infestation risks destabilizing the U.S. livestock industry at a time of historic vulnerability. Because the parasite feeds on living tissue, it can cause severe injury or death to livestock and wildlife if left untreated.

The New World screwworm, known scientifically as Cochliomyia hominivorax, is a flesh-eating parasite that affects cattle and other livestock ^[1]. Reports of the fly first surfaced in 2025, but the situation intensified in July 2026 ^[2]. The parasite was detected in South Texas, specifically in areas near the U.S.-Mexico border ^[1].

Agricultural officials are concerned because the Texas cattle industry is valued at $15 billion ^[2]. This threat arrives as the U.S. cattle herd is at its lowest level in 75 years ^[3]. The parasite likely entered the U.S. from Mexico, potentially through wildlife-livestock interactions ^[4].

Previous attempts to prevent the spread included closing the southern border to cattle imports for more than a year ^[5]. Despite these measures, the parasite continued to spread. The risk has now extended beyond livestock, with the confirmation of one human case of screwworm in the U.S. ^[2].

Federal efforts to combat the fly often involve the release of sterile insects to disrupt the breeding cycle. The spread of the parasite has also led to political friction regarding border controls and the efficacy of the cattle ban ^[4].