Texas lifts more screwworm infested zones as US case count stands at 49 and a billion sterile flies have been released

The US Department of Agriculture and the Texas Animal Health Commission are releasing New World screwworm infested zones in Texas as areas go without new cases, with the most recent zone lifted on 21 September and others still in force. The first US case was found in a newborn calf in Zavala County on 3 June 2026; the calf has recovered and that zone has been released.

Since 3 June there have been 49 confirmed cases in the United States, 48 in Texas and one in New Mexico, in cattle, sheep, goats, dogs and, most recently, a horse. In each zone animals are subject to inspection and movement requirements, sterile flies are released and fly traps keep watch; more than one billion sterile screwworm flies have been released so far.

"The Texas Animal Health Commission has been an outstanding partner throughout our response to New World screwworm," said Dudley Hoskins, USDA Under Secretary for Marketing and Regulatory Programs. "Thanks to this strong federal-state partnership, we've been able to identify cases early, respond aggressively, and slow the spread of NWS across affected areas." USDA reminded animal owners that early detection halts outbreaks.

Stephen Diebel, president of the Texas & Southwestern Cattle Raisers Association, said the release of infested zones "marks an important step forward and restores continuity of business in these areas", adding: "We know the fight is not over, but we are grateful for this progress and remain committed to protecting the livestock industry and pushing NWS back to the Darien Gap."

The border is reopening in step. The Douglas, Arizona, port of entry took Mexican cattle again from 24 August, and after touring the Santa Teresa livestock port in New Mexico on 17 September Agriculture Secretary Brooke Rollins announced it will reopen on Thursday 24 September; USDA has said the timeline stays flexible and depends on Mexico meeting its action-plan milestones. Reporting by Jennifer Carrico, DTN senior livestock editor.

Photo: Judy Gallagher / Wikimedia Commons (CC BY 2.0)

Source: DTN / Progressive Farmer