USDA Confirms Second New World Screwworm Detection in Zavala County, Texas

The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed a second detection of New World Screwworm (NWS) in Texas. The confirmed case was identified in a one-month-old calf in Zavala County, approximately 5.6 miles from the first confirmed detection announced on June 3, 2026.

As part of the established NWS eradication strategy, USDA began releasing sterile flies over the affected area on June 4. These aerial release missions are dispersing 2 million sterile screwworm flies twice per week to disrupt the pest’s lifecycle and prevent further spread.

In addition to aerial releases, USDA is shipping another 4 million sterile flies per week to Texas. These flies will be deployed through 24 ground release chambers strategically placed in and around the detection zone to maximize the effectiveness of eradication efforts.

Members are encouraged to closely monitor animals for suspicious wounds, maggots, larvae, eggs, unusual drainage, or other signs of infestation. If you observe any suspicious wounds, maggots, or infestations in your animals or herd, contact your veterinarian immediately. Early detection and reporting are critical in preventing the spread of NWS.

TAHC has also modified the Executive Director Order related to NWS response and containment efforts. Members are encouraged to review the adopted changes and stay informed of any requirements that may impact animal movement and management practices.