Earlier this fall, the New World screwworm – the flesh-burrowing larva of a blowfly (Cochliomyia hominivorax) – was detected in cattle in Mexico just 70 miles from the U.S. border. Most recently, in late November, another case was confirmed in Nuevo León, a state of Mexico adjacent to Texas.

While the screwworm is not currently present in the U.S., Mexico and Central American countries have been reeling due to the resurgent parasite. There have been more than 144,000 cases in animals and over 1,100 in humans during this outbreak dating to 2023 – and the cases continue to track northward.

Members of the California agriculture community are just as worried as their counterparts in Texas, where an outbreak could cost livestock producers $732 million per year and cause up to $1.8 billion in losses for the Texas economy, according to U.S. Department of Agriculture estimates.

Among California’s top gross-value commodities in 2024, dairy products/milk are number one ($8.61 billion) and cattle and calves are number four ($4.98 billion) – both categories that could be most affected by the screwworm.

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