The U.S. is preparing to release billions of flies from planes over southern Texas and parts of Mexico in a large-scale effort to combat a dangerous, flesh-eating maggot.
The maggot, which poses a serious threat to the U.S. beef industry, also endangers wildlife, pets, and, in rare cases, humans.
The intended target is the larva of the New World screwworm fly, a parasite that feeds on the living tissue of warm-blooded animals.
For the plan, the U.S. Department of Agriculture will sterilize adult male flies using radiation and then release them into the wild. When these sterile males mate with wild females, the resulting eggs won’t develop, gradually reducing the fly population until it dies out completely.
Not only is it effective, but it’s also much more environmentally friendly than using pesticides. In fact, it’s the same method that the U.S. and other countries used to eradicate the fly decades ago.
For years, a factory in Panama supplied sterile flies that successfully kept the screwworm population under control. However, the pest reappeared in southern Mexico in late 2024.
The USDA plans on opening the new screwworm fly facility by July 2026. They will also be establishing a distribution center in southern Texas, which will allow for the import of sterile flies from Panama if needed.
Danger to the U.S. Beef Industry
What makes the New World screwworm fly especially dangerous is that its larvae feed on living flesh. After mating, females lay their eggs in open wounds on animals.
Upon hatching, the maggots dig into the wound and begin consuming the animal’s living tissue.
According to the president of the American Veterinary Medical Association, the infestation can “kill a thousand-pound bovine in less than two weeks.”
While effective treatments do exist, infected animals still endure intense pain and suffering during the process.
Breeding More Flies
Decades ago, the U.S. operated fly factories in Texas and Florida, but they were eventually shut down after the screwworm was successfully eradicated.
Currently, the fly facility in Panama can produce up to 117 million sterile flies each week. However, the USDA aims to increase production to at least 400 million flies a week.
To reach that goal, they will be investing $21 million to convert an existing sterile fruit fly facility in southern Mexico into one that produces sterile screwworm flies. They will also be investing an $8.5 million toward a second facility in Texas.
While raising large colonies of flies is relatively simple, the challenge lies in providing the females with the necessary cues so that they will lay their eggs under controlled conditions.
