U.S. Department of Agriculture officials detected larvae of a meat-eating parasitic fly in a three-week-old calf in Texas on June 3 [1, 2].
The discovery of the New World screwworm fly is significant because the parasite can devastate livestock populations and potentially trigger spikes in beef prices [2, 3].
Officials located the infestation near La Prairie, approximately 48 kilometers from the Mexico-U.S. border [3]. The USDA has established a quarantine radius of 20 kilometers around the site to prevent further spread [1].
This event marks the first detection of the parasite in the U.S. in roughly 10 years [2]. However, other reports suggest the detection is the first in 60 years [3]. The discrepancy in timing highlights the rarity of the parasite's presence in the region.
A USDA spokesperson said the screwworm fly lays hundreds of eggs in the wounds of animals, and the hatched larvae eat living flesh, which can lead to the animal's death [2]. Authorities said the fly likely entered the U.S. from Mexico, where infestations are currently rising [2].
While the parasite primarily affects livestock, the Centers for Disease Control and Prevention noted that human infections are rare [2]. The CDC reported one case in August 2025 involving an individual returning to the U.S. from Central America [2].
Industry analysts said that if the parasitic fly becomes widespread, it could accelerate the rise of beef prices [2].
“The screwworm fly lays hundreds of eggs in the wounds of animals, and the hatched larvae eat living flesh.”
The reappearance of the New World screwworm in Texas underscores the vulnerability of the U.S. agricultural supply chain to transboundary pests. Because the parasite targets living tissue rather than dead flesh, it can rapidly incapacitate healthy livestock, creating a high-risk scenario for cattle ranchers. The proximity of the detection to the Mexican border suggests a failure in current bio-security barriers or a surge in the parasite's prevalence in neighboring regions, potentially necessitating more stringent livestock inspections and regional quarantine protocols to avoid economic instability in the meat market.
