Revision History

The New World screwworm, a parasitic fly eradicated from U.S. livestock in 1966, was confirmed in two Texas calves in June 2026 — the first domestic cases in six decades. The outbreak, which marched northward from Panama through Central America and Mexico after a collapse in international containment, now threatens an already-strained cattle industry with billions in potential losses and has exposed years of underfunding in the biosecurity buffer zone designed to prevent exactly this scenario.