Spotlight on New World Screwworm

By DTN Staff

On June 3, 2026, USDA confirmed the first U.S. case of New World screwworm (NWS) -- spread by a flesh-eating parasitic fly -- had been detected in a calf in south Texas, roughly 50 miles from the Mexican border. It was the first confirmed case in the country since the pest was eradicated in the U.S. decades ago, but it was not a surprise.

U.S. agriculture officials and industry stakeholders had long warned that the day was coming. After NWS cases began emerging in Panama, Costa Rica, Nicaragua and Honduras, Mexico reported its first case in 2024. Since early 2025, the pest has been steadily advancing northward, and USDA and its partners have been racing to slow its spread and prevent it from regaining a foothold on U.S. soil.

USDA and livestock experts have been clear: NWS is not a food safety issue -- it is a food production issue. A widespread outbreak could cost the U.S. cattle industry billions of dollars, with the heaviest impact on Texas, the nation's top cattle-producing state, and could significantly disrupt the U.S. beef supply chain.

DTN has been closely tracking the northward spread of New World screwworm and the ongoing efforts to protect U.S. livestock. On this page, you will find links to DTN's past and latest reporting on NWS, as well as resources on how to report a suspected case and steps producers can take to protect their animals.

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Links to the latest DTN stories on New World Screwworm:

-- "USDA Reports 2 More Texas NWS Cases," https://www.dtnpf.com/… (6/8/2026)

-- "Abbott Declares Disaster as NWS Spreads," https://www.dtnpf.com/… (6/5/2026)

-- "NWS in Texas Puts Industry on Alert," https://www.dtnpf.com/… (6/4/2026)

-- "USDA Confirms First US NWS Case," https://www.dtnpf.com/… (6/3/2026)

-- "USDA Tests Possible US NWS Case," https://www.dtnpf.com/… (6/3/2026)

-- Call the Market: "At This Point, It's Not If But When New World Screwworm Appears in US," https://www.dtnpf.com/… (6/3/2026)

-- "Latest NWS Case Is 25 Miles From US," https://www.dtnpf.com/… (6/2/2026)

-- "Texas NWS Facility Breaks Ground," https://www.dtnpf.com/… (4/20/2026)

-- "Sterile Flies Combat NWS Spread," https://www.dtnpf.com/… (2/10/2026)

-- Ag Weather Forum: "Winter Storm May Help Control New World Screwworm," https://www.dtnpf.com/… (1/27/2026)

-- Top 10 Ag Stories of 2025: No. 8: "NWS Causes Threat to US Livestock Industry," https://www.dtnpf.com/… (12/22/2025)

-- "NWS Prevention, Eradication Important," https://www.dtnpf.com/… (12/10/2025)

-- Sort and Cull: "Feeder Cattle Prices May Skyrocket as APHIS Restricts Mexican Cattle Imports due to New World Screwworm," https://www.dtnpf.com/… (11/25/2024)

-- "Border Closed: Texas Feedlots Can't Get Cattle From Mexico," https://www.dtnpf.com/… (10/31/2025)

-- Call the Market: "Does the Feeder Cattle Complex Have Enough Support to Break Through Resistance?" https://www.dtnpf.com/… (10/8/2025)

-- "Tight Supplies Lead to Profitable Beef Industry," https://www.dtnpf.com/… (10/6/2025)

-- "Conditional Approval Allows Use for NWS Fight," https://www.dtnpf.com/… (10/1/2025)

-- "Threat Looms as Screwworm Nears US," https://www.dtnpf.com/… (9/22/2025)

-- Call the Market: "Will Feeder Cattle Prices Keep Rising? Two Critical Market Factors to Watch," https://www.dtnpf.com/… (8/27/2025)

-- Sort and Cull: "New World Screwworm Wasn't on the Cattle Market's Bingo Card," https://www.dtnpf.com/… (8/25/2025)

-- "US Confirms First NWS Human Case," https://www.dtnpf.com/… (8/25/2025)

-- Sort and Cull: "USDA's Screwworm Fight Matters: Why USDA's $850M Plan Is a Smart Move," https://www.dtnpf.com/… (8/22/2025)

-- "USDA Invests $850M in NWS Fight," https://www.dtnpf.com/… (8/18/2025)

-- "NWS Parasite Moves Closer to US Cattle," https://www.dtnpf.com/… (8/4/2025)

-- "USDA Halts Mexican Cattle Imports," https://www.dtnpf.com/… (7/14/2025)

-- "Border to Reopen to Mexican Cattle," https://www.dtnpf.com/… (6/30/2025)

-- "USDA Facility Will Help Combat NWS," https://www.dtnpf.com/… (6/23/2025)

-- "Ag Secretary Says More Effort Needed to Attack New World Screwworm in Mexico," https://www.dtnpf.com/… (6/12/2025)

-- "WOAH: Invest in Prevention, Not Crisis," https://www.dtnpf.com/… (5/18/2026)

-- "TX Lawmakers Propose Bill to Fight NWS," https://www.dtnpf.com/… (5/14/2025)

-- "NWS Closer: Border Closed for Animals," https://www.dtnpf.com/… (5/12/2025)

-- "NWS Agreement Keeps Cattle Imports Open," https://www.dtnpf.com/… (5/5/2025)

-- "Rollins Warns Mexico Over Screwworm," https://www.dtnpf.com/… (4/27/2025)

-- "Sterile Flies Help With NWS Prevention," https://www.dtnpf.com/… (2/27/2025)

-- "Protocol to Prevent Screwworm Spread," https://www.dtnpf.com/… (2/14/2025)

-- Sort and Cull: "Live Cattle Imports From Mexico Still on Hold Due to New World Screwworm Case," https://www.dtnpf.com/… (1/10/2025)

-- Sort and Cull: "Feeder Cattle Prices May Skyrocket as APHIS Restricts Mexican Cattle Imports due to New World Screwworm," https://www.dtnpf.com/… (11/25/2024)

-- "US Halts Imports of Mexican Cattle," https://www.dtnpf.com/… (11/25/2024)

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Here are links to useful information for livestock producers on how to identify and report suspected NWS cases and how to protect your livestock from infestation:

-- USDA Animal and Plant Health Inspection Service (APHIS), including a fact sheet and how to report suspected cases of NWS: https://www.aphis.usda.gov/…

-- U.S. Food and Drug Administration (FDA) Animal Drugs for New World Screwworm: https://www.fda.gov/…

-- Cattlemen's Beef Board and National Cattlemen's Beef Association: New World Screwworm Producer Resources, including how to identify New World Screwworm: https://www.beefitswhatsfordinner.com/…

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Additional information on NWS:

-- Canadian Food Inspection Agency news release on measures taken by Canada to prevent spread of New World screwworm: https://www.canada.ca/…

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