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USDA confirms New World screwworm in Arizona dog

By Drooid · Oct 29, 2026 · How we work

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Summary

USDA confirmed a New World screwworm infestation in a dog in Cochise County, Arizona.
USDA imposed a 20-km movement restriction zone around the case.
USDA released about one million sterile screwworm flies in the county.
USDA reported 71 screwworm cases since June, with 18 active, including 10 in New Mexico.
USDA plans to restart livestock imports at Nogales, Arizona on November 30 if conditions allow.

Summary

Sheep on New Mexico State University campus were confirmed infected with New World screwworm.
A cow at an off-campus site in Doña Ana County also tested positive.
Officials say wounds from branding, castration, dehorning, surgery or newborn navels raise infestation risk.
Animals in the 12.4-mile infested zones must be inspected within five days and treated before movement.

History

USDA entomologists Edward Knipling and Raymond Bushland developed the sterile-insect technique, first field-tested in Curaçao in 1954 and eliminating screwworm from the southern United States by 1966. Between 1962 and 1975 the program released over 94 billion sterile flies, creating a barrier south of Panama’s Darien Gap. In 2026 Arizona and New Mexico outbreaks led USDA-APHIS to restart weekly releases near Cochise County.

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USDA entomologists Edward Knipling and Raymond Bushland developed the sterile-insect technique, first field-tested in Curaçao in 1954 and eliminating screwworm from the southern United States by 1966. Between 1962 and 1975 the program released over 94 billion sterile flies, creating a barrier south of Panama’s Darien Gap. In 2026 Arizona and New Mexico outbreaks led USDA-APHIS to restart weekly releases near Cochise County.

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