REDFIELD, Iowa (DTN) -- As the New World screwworm (NWS) threat moves closer to the United States, Texas cattle producer Benton England said it is important to be on the lookout.

"I don't think we are near ready to fight the screwworm problem if it gets across the border," England said. He and his family run a Brahman ranch 11 miles north of the Mexico border at Mercedes, Texas. He said he heard about how bad the pest was from his grandfather who dealt with the problem many years ago.

"Secretary (Brooke) Rollins has put more emphasis on fighting the screwworm problem," England added. "It is killing the Mexican beef industry with the closed border. They are having a hard time managing the extra cattle and the flies."

NEWEST CASES IN TAMAULIPAS

Mexican authorities confirmed an NWS case in a seven-year-old bovine and a 6-day-old calf both on Jan. 5. The older animal was in the state of Tamaulipas, about 215 miles south of the Texas border and the younger was in the same state, but approximately 197 miles from the border. These cattle residing in that area and being infected with NWS show the pest is moving closer. The cases which had previously been near the U.S. border were cattle that had been transported to the area from further south in Mexico.

While NWS has not crossed into the U.S., Mexico continues to fight the problem. As of Jan. 7, 2026, Mexico has had 13,234 cases, with 492 current active animal cases. The sterile insect technique is being used in these areas in hope to slow the movement.

"The screwworm now may be moving closer on its own, with no apparent link to commercial animal movement," said Texas Agricultural Commissioner Sid Miller. "Texas producers must act now -- stay informed, stay vigilant, and prepare immediately. We cannot drop our guard for even a moment."

US, MEXICO WORK TOGETHER

Mexican officials said there is no evidence of an established screwworm population in Tampaulipas. The USDA's Animal and Plant Health Inspection Service (APHIS) and Mexico's National Service for Health, Safety and Agro-Food Quality (SENASICA) are working together to investigate the cases and releasing sterile flies to stop the spread.

The Texas Department of Agriculture continues to stress to livestock producers the importance of inspecting animals and treating any livestock with injuries or wounds.

England said he and his family have discussed what actions should be taken on their ranch if the pest does enter the country. "We must be very aware of what's going on with our animals to stop the movement of screwworm. Doctoring anything that needs it to prevent an infestation and especially be careful with newborn calves," he said. "Winter may hold it back some, but we still have to keep an eye out. We can't afford to have this problem affect our beef industry like it has across the border."

Construction continues on a sterile fly production facility at Moore Airbase in Edinburg, Texas, with completion expected in early 2027. A sterile fly distribution facility at the same location is expected to be in use in early 2026. The production facility will help provide sterile flies to combat the pest. Since the insect only mates once in its lifetime, releasing sterile males to mate with the females helps reduce the population.

NWS CAN CAUSE EXTENSIVE DAMAGE

NWS are fly larvae that infest living tissue of warm-blooded animals, causing infection. According to APHIS, these maggots will burrow into a wound, feeding as they go, and do extensive damage by tearing the host's tissue with sharp mouth hooks. The wound becomes larger and deeper. NWS can cause serious, even deadly damage to the animal.

The adult screwworm flies are about the size of a common housefly with orange eyes, a metallic blue or green body, and three dark stripes along their backs.

Affected mammals and birds show signs of irritated behavior, head shaking, smell of decay, evidence of fly strike, and presence of fly larvae in wounds.

USDA eradicated NWS from the United States in 1966 using the sterile insect technique and it was used successfully again in 2016 in the southern Florida Keys when found in deer. This process continues to be used in Mexico and Latin America.

"The continued detections of New World screwworm near the Texas border are grim reminders of the serious threat this pest poses to our state," Miller said. "I will continue to support and advocate for federal efforts to expand sterile insect fly production and infrastructure, because this proven strategy is key to the long-term eradication of New World screwworm."

The Food and Drug Administration continues to work with animal health companies to give conditional or emergency use approval for medicines to be used to treat animals affected by New World screwworm.

For more information, visit https://www.aphis.usda.gov/….

Jennifer Carrico can be reached at jennifer.carrico@dtn.com

Follow her on social platform X @JennCattleGal

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