MT Department of Livestock Issues Emergency Order for Screwworm

By now you have probably heard about an invasive species disease in the southern part of the United States that is unfortunately making a comeback.  The Cochliomyia hominivorax, or New World Screwworm (NWS) has been found in livestock in Texas and surrounding states in other animals including pets.

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With the reemergence of this disease, the Montana Department of Livestock has issued a new emergency order for NWS, effective immediately across the state.  The new order limits livestock from entering the state from other states that have seen an NWS outbreak.

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MT Department of Livestock Issues Emergency Order for Screwworm

On Friday, June 12, 2026, the department stated through a press release that "circumstances exist constituting an imminent peril to animal health and welfare in the State of Montana and is issuing an emergency order stopping the entry of animals from states with NWS infestations until specific myiasis control measures have been met."

Joel Angel Juarez, Getty Images

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In making the declaration, the state veterinarian included that animals restricted would include "cattle, horses, mules, asses, other equids, sheep, llamas, alpacas, bison, swine, ostriches, rheas, emus, goats, alternative livestock as defined in § 87-4-406, MCA, dogs, cats, rabbits, rodents, game animals, fur-bearing and wild animals, and poultry and other birds."

Learning More About the NWS from the Montana Department of Livestock

The New World Screwworm has been eradicated in the state of Montana and the US since 1966, but with the reintroduction of it, the Department of Livestock says that it "has the potential to cause significant economic damage to the livestock industry in the United States."

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NWS is spread through flies that lays eggs in open wounds and orifices of any warm-blooded animal.  The eggs then hatch into larvae, which feed on living tissue causing severe injury to and potential death of infested animals, and even humans.  Learn more about the NWS through the Montana Department of Livestock here.