Newton Warns Screwworm Fight Requires Massive Expansion in Sterile Fly Production
Farm Bureau economist says current capacity falls well short of what is needed to stop northward spread
During the June 12 edition of AgriTalk (link), American Farm Bureau Federation chief economist John Newton emphasized that the battle against New World screwworm will ultimately hinge on one factor: producing and releasing enough sterile flies to overwhelm the wild population and break the insect’s reproductive cycle.
Newton noted that the current sterile fly production system in Panama was designed to maintain a biological barrier in Central America, not to combat a widespread outbreak stretching across Mexico and now into the United States. According to Newton, the scale of the current infestation requires substantially more sterile flies than are presently available, making expanded production capacity an urgent priority.
The challenge is enormous. The sterile insect technique works because female screwworm flies mate only once. If they mate with a sterilized male, they produce no offspring, causing populations to collapse over time. The strategy successfully eradicated New World screwworm from the United States in the 1960s and later pushed the pest south through Mexico and Central America.
However, Newton argued that today’s outbreak is occurring across a much larger geographic footprint than the Panama containment zone. The existing facility in Panama is producing only a fraction of the flies now needed to suppress populations moving northward. Recent reports indicate current production capacity is roughly one-fifth of what experts believe may ultimately be required for an aggressive eradication effort.
The key quote from came from John Newton when discussing the need for sterile flies to eradicate New World screwworm: “You need the flies, and that’s what we don’t have enough. And I’ll share with you, when we had this, you know, 60 years ago… it took 96 billion flies to eradicate New World screwworm the first time, so we’ve got some work to do.”
When host Sean Heaney asked him to repeat the number, Newton responded: “Don’t tell anybody outside of agriculture now, Sean, but it was 96 billion flies over a 13-year period.”
For context, Newton was answering a question about whether the next step in the USDA response is ramping up sterile-fly production. He agreed that substantially more sterile flies are needed and used the historical eradication campaign as an example of the scale required.
That reality explains why USDA has moved aggressively to expand infrastructure. The department has announced construction of a new sterile fly production facility in Edinburg, Texas, that is expected to eventually produce up to 300 million sterile flies per week. USDA is also upgrading facilities in Mexico and investing heavily in additional production technologies.
Newton’s comments highlight a key issue for livestock producers: the screwworm battle is not simply about detecting and treating infected animals. It is fundamentally a logistics and manufacturing challenge. The faster sterile fly production can be expanded, the greater the chances of re-establishing a biological barrier and preventing the pest from becoming entrenched in the southern United States.
As noted, the only sterile fly facility is a plant in Panama that’s producing only a fraction of the insects needed to mount an effective response. The concern is over how far screwworm will spread before the U.S.’ plan is fully operational.
USDA Secretary Brooke Rollins said last week that the U.S. is “not going to be able to eradicate it until we’ve got the couple hundred million more flies coming in, but we will be able to contain it.” She added that she doesn’t “have a good enough sense yet” of how far screwworm might spread in the meantime.
Others see more urgency in getting the Texas plant up and running.
For cattle producers, the stakes are significant. New World screwworm larvae feed on living tissue, creating severe wounds that can kill livestock if left untreated. The parasite has already spread rapidly north from Panama since 2023, leading to 12 confirmed cases in Texas and New Mexico and prompting USDA to launch a multibillion-dollar-plus response effort.
The bottom line from Newton’s AgriTalk assessment was straightforward: the United States and its partners know how to eradicate screwworms because they have done it before. The question now is whether enough sterile flies can be produced quickly enough to stay ahead of the pest’s expansion.
