US screwworm cases rise as outbreak spreads beyond initial contamination zones

Dyed screwworm fly pupae are seen as a sterile fly dispersal station is placed by the US Department of Agriculture to combat the spread of the New World screwworm fly on grounds of a ranch near La Pryor, Texas, on 11 June 2026. Photograph: Eric Gay/AP

Screwworm cases are rising in the US as the outbreak spreads beyond the initial contamination zones.

Twelve animal cases have been confirmed so far, a significant increase from the first case detected in a calf in south Texas on 3 June. The growing number of infections has alarmed agricultural experts, who warn that a wider outbreak could have serious consequences for the Texas beef industry.