The U.S. Department of Agriculture (USDA) announced it will phasedly reopen cattle, bison, and equine imports from Mexico beginning July7, following a May suspension triggered by the northward spread of the New World screwworm (Cochliomyia hominivorax). With over 100million sterile male flies released weekly and no further northward movement detected in eight weeks, USDA and Mexico's SENASICA are reinforcing border biosecurity to protect U.S. livestock, wildlife, and supply chains.

Estrategia y cronograma de reanudación

July7: Douglas, Arizona opens first for cattle, bison, and equine imports-chosen for its historical collaboration and low pest risk.

Subsequent openings are scheduled for July14 (Columbus NM), July21 (Santa Teresa NM), August18 (Del Rio TX), and September15 (Laredo TX), contingent on surveillance results.

Reason for Closure & Control Measures
USDA suspended imports on May11 after the parasite was detected moving northward from Central America. In response, APHIS and SENASICA deployed a five-part control plan-sterile fly dispersal, enhanced surveillance, quarantine enforcement, outreach campaigns, and binational coordination. APHIS deployed five mobile inspection teams across key ports to verify compliance and risk mitigation.

Investment in Sterile-Fly Production & Facilities

U.S. Facility in South Texas
A new $8.5 million sterile-fly facility is being built at Moore Air Base in Texas. Expected to be operational by the end of 2025, this site will reinforce loterm response capacity and regional pest suppression.

Mexico's Metapa Facility Expansion
An additional $21 million is being invested to upgrade Mexico's Metapa fruit-fly facility. By mid-2026, it will be able to produce between 60 to 100 million sterile flies per week, doubling output capacity and improving eradication outcomes in southern Mexico.

Sterile-Insect Technique (SIT)
The technique releases sterilized male screwworm flies into the wild. These males fail to reproduce, disrupting the life cycle of wild populations. This method was used successfully to eradicate the pest from the U.S. by 1966 and remains the backbone of USDA's prevention strategy.

Impacts on U.S. Livestock & Policy

Animal Health Risks
Screwworm larvae invade open wounds and living tissue in livestock, causing severe infections, weight loss, reproductive failures, and even death. The parasite also threatens wildlife, companion animals, and in rare cases, humans. The last major outbreak in U.S. territory required decades of intervention and billions in economic recovery.

Economic Safeguards
The current phased reopening aims to reduce economic disruptions while maintaining biosecurity. Livestock producers depend on Mexican feeder cattle to stabilize input costs and fulfill market demand. USDA's efforts also align with broader farm bill policy objectives-supporting commodity price stability, animal health programs, and sustainable agriculture initiatives.

Texas Leadership & Federal Cooperation

State-Level Coordination
Texas has played a proactive role in containment. Governor Greg Abbott activated a joint screwworm response team involving the Texas Animal Health Commission (TAHC) and Texas Parks and Wildlife Department (TPWD). These agencies are coordinating inspections, public outreach, and emergency containment protocols.

STOP Screwworms Act
Senator John Cornyn introduced the STOP Screwworms Act in Congress, designed to authorize federal funding for new sterile-fly facilities within the U.S. This legislation emphasizes the need for rapid domestic capacity in the face of escalating border biosecurity challenges.

USDA and APHIS will continue conducting 30-day risk assessments prior to each additional port opening. These checks include inspections for larval activity, tissue samples from cattle, and movement documentation from Mexican authorities. Success hinges on the ability to maintain sterile-fly dispersal at scale-over 500 million per week-while preventing any new cases north of the dispersal line.

As cattle imports resume, ongoing vigilance, regional coordination, and early detection will be essential to protect the U.S. livestock economy. The screwworm threat has underscored the importance of cross-border disease management and loterm investment in pest prevention infrastructure.

The phased reopening of livestock trade between the U.S. and Mexico offers cautious optimism for ranchers and policymakers. Backed by increased sterile-fly production, enhanced surveillance, and state-federal cooperation, the response aims to prevent a re-emergence of the devastating New World screwworm while restoring critical agricultural trade flows. As the USDA monitors risk zones and invests in loterm capacity, this episode reinforces the value of proactive biosecurity policy in sustaining U.S. agricultural resilience.