In a story that sounds more like a scene from a dystopian thriller than a mission of mercy, the U.S. government is preparing to breed and release billions of sterilized flies over southern Texas and Mexico. But this isn’t chaos — it’s a calculated effort to protect life. Behind this strange science is a deeply moral mission: to preserve animals, prevent suffering, and guard human health. And for Catholics, it’s a reminder that even the smallest creatures of God’s creation can be part of His plan to heal and defend.
The threat is real. The New World screwworm fly is a flesh-eating parasite whose larvae feed on the living tissue of warm-blooded animals. Unlike typical maggots that consume decaying flesh, these pests invade open wounds and mucous membranes, often leading to unspeakable pain, infection, and even death — not only in livestock but in wildlife, household pets, and humans.
“A thousand-pound bovine can be dead from this in two weeks,” said Michael Bailey, president-elect of the American Veterinary Medical Association. Infestations, while treatable, can cripple the animal with pain and lead to death if untreated. For ranchers and farmers, whose vocation calls them to be stewards of creation, such infestations are more than economic blows — they are spiritual burdens, watching helplessly as creatures in their care suffer.
To respond, the U.S. Department of Agriculture (USDA) is turning to a method of pest control that doesn’t poison the environment but instead uses the fly’s own biology against it. The plan: breed massive numbers of adult male screwworm flies, sterilize them using radiation, and release them into the wild. Once released, these sterile males mate with wild females, but no offspring are born. Since female flies only mate once in their brief adult lives, the population eventually collapses.
“It’s an exceptionally good technology,” said Edwin Burgess, an assistant professor at the University of Florida who studies parasites in animals. “It’s an all-time great in terms of translating science to solve some kind of large problem,” according to NBC News.
This method isn’t new. Between 1962 and 1975, the U.S. and Mexico released over 94 billion sterile flies to eradicate the screwworm pest across the Americas. This success led to the closing of U.S.-based fly factories in Florida and Texas once the threat had passed. But now, with signs of screwworm reappearing in southern Mexico, the USDA is moving swiftly to prevent a resurgence.
To achieve this, the USDA plans to build a new sterile fly facility in southern Mexico by July 2026 and open a distribution center in southern Texas by the end of this year. The factory in Panama — which can already produce up to 117 million flies per week — will help supply the effort in the meantime. The USDA aims to eventually ramp up production to 400 million flies per week, investing $8.5 million in Texas and $21 million to convert a facility in Mexico.
Some may question why so much time, effort, and money — not to mention flies — should be spent on such an endeavor. But the answer lies in the sacred duty to protect life. The Church teaches that all creation reflects God’s glory. In Laudato Si’, Pope Francis reminds us that “our mistreatment of the natural environment is a betrayal of the gift of life” (§6). This program doesn’t fight creation — it works with it.
Instead of spraying pesticides or relying on harmful chemicals, the USDA is taking what may be called a more natural approach. As Cassandra Olds, an assistant professor of entomology at Kansas State University, explained: “You’ve got to give the female the cues that she needs to lay her eggs, and then the larvae have to have enough nutrients.” That’s why, in the sterile fly factories, the larvae are fed carefully balanced diets and allowed to develop in controlled environments using food mixes of egg powder and cattle blood cells.
Security is also critical. Sonja Swiger of Texas A&M’s Extension Service noted that the breeding facilities must ensure that fertile flies — used only for breeding — never escape. An incident in May underscored the risks: a plane distributing sterile flies near the Mexico-Guatemala border crashed, tragically killing three people. It’s a reminder of the human cost that can be involved in protecting life on a large scale.
Dropping the flies is still done largely the same way it was decades ago: crates loaded onto planes and dropped mid-flight. In the 1950s, scientists dropped paper cups filled with flies using special chutes. Today, the “Whiz Packer” — a machine that loads boxes — continues to be used.
This strange but noble work is being hailed by scientists and agricultural leaders alike. Burgess called the sterile fly program one of the USDA’s “crowning achievements,” a sentiment echoed by many who remember the horrors of screwworm infestation.
For Catholics, this entire story invites us to reflect on our role as stewards of the Earth. God gave humanity “dominion” over creation (Genesis 1:28), but that dominion is not one of domination — it’s one of care. By using science rooted in respect for life and the limits of nature, the USDA’s program offers a model for how humanity can work alongside God’s design rather than against it.
As Burgess wisely warned, “Something we think we have complete control over — and we have declared a triumph and victory over — can always rear its ugly head again.” In other words, vigilance, humility, and stewardship must never end.
In these billions of flies, Catholics might glimpse not a horror story — but a parable. Even the smallest creatures can help save life. Even strange tools can serve sacred purposes. And even science, when ordered rightly, can be a powerful instrument of God’s mercy.
