The U.S. Department of Agriculture and Texas officials confirmed the detection of the New World screwworm in a calf on June 4, 2026 [1, 2].

The discovery marks the first confirmed case of the flesh-eating parasite in the U.S. in decades [5]. Because the pest targets living tissue, its presence poses a significant risk to livestock and wildlife if not contained quickly.

Officials found the larvae in the umbilical area of a calf that was three weeks old [2, 4]. The animal was located in Zavala County, Texas [1, 3].

The New World screwworm is a parasite that differs from common blowflies because its larvae feed on the living flesh of warm-blooded animals. This can lead to severe tissue damage and death if left untreated.

Agricultural authorities are currently acting to eradicate the pest and prevent further spread. Despite the severity of the parasite, officials said there is no immediate threat of a mass infestation [5].

Texas officials are monitoring the affected area in Zavala County to ensure the infestation remains isolated. The USDA is coordinating with state agencies to implement containment protocols designed to protect the broader livestock industry from the parasite's impact.

“The discovery marks the first confirmed case of the flesh-eating parasite in the U.S. in decades.”

The reappearance of the New World screwworm threatens the stability of the U.S. livestock industry, which relies on the absence of such aggressive parasites to maintain animal health and productivity. While officials believe the current risk of a mass outbreak is low, the incident highlights the vulnerability of agricultural borders to invasive species and the necessity of rigorous surveillance to prevent economic losses in the cattle sector.