The federal government is quietly breeding billions of flies in an ongoing effort to stop a dangerous parasite that threatens livestock and wildlife in Texas and along the southern border.
The project, run by the U.S. Department of Agriculture (USDA) with support from Mexico, targets the screwworm fly, a lethal parasite that burrows into open wounds and can kill cattle, deer, and other large animals in days.
To expand the program, the USDA is building a new $8.5 million insect dispersal center in Texas, while also upgrading a site in southern Mexico to boost fly production and sterilization capacity.
The plan? Release waves of sterile male screwworms into infected regions so the wild female population can’t reproduce — effectively collapsing future generations of the pest.
117 Million Flies Per Week
The U.S. currently produces and sterilizes 117 million screwworm flies every week at a Panama-based lab, then air-drops them by plane over Texas, Florida, and parts of Central America.
After sterilization, the flies are chilled and sorted by sex, with the stronger male flies dropped over hotspots. Female flies are excluded because they’re weak fliers.
This aggressive strategy is expected to continue through 2026.
A Battle With Real Stakes
The screwworm is no joke. The parasite lays eggs inside open wounds, and the maggots eat their host alive, causing deadly infections and enormous pain for animals.
In 2016, an outbreak in Florida wiped out over 130 endangered deer before officials could contain it. If not for this program, that outbreak could have spread across the Southeast.
Protecting U.S. Livestock
Cattle and livestock are the main targets of this parasite, and U.S. ranchers could face devastating losses if the screwworm gains a foothold again.
The USDA says its goal is to stop the parasite at the source before it crosses further into U.S. territory.
Areas of operation include:
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Southern Texas
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The Florida Keys
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Northern Mexico
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Parts of Central America
