A Dallas biotech firm best known for trying to “de-extinct” the Woolly Mammoth has a plan to wipe out New World Screwworm (NWS) in the US forever. “Colossal Biosciences” is advancing a genetic solution to collapse NWS populations by spreading female infertility through the fly’s own gene pool. What’s more, the company says its scheme could rid the pest from the US within a year.
In early June 2026, USDA’s Animal and Plant Health Inspection Service (APHIS) confirmed NWS had been found in Texas, the first US detection in roughly half a century. At least a dozen cases have been confirmed since, and experts are braced for the numbers to keep climbing. The USDA is fighting the pest on several fronts, including border controls and intensified surveillance of livestock and wildlife.
USDA’s primary tool is the agency’s sterile-fly releases, aka “Sterile Fly Technique” or SIT. The USDA successfully used SIT to initially eliminate the NWS starting in the 1950s. The strategy relied on rearing and releasing hundreds of millions of sterile male flies each week so that wild females—who usually mate only once—produced no viable offspring, causing screwworm populations to crash and disappear from each region in turn. The US has managed to keep the fly at bay using SIT for 60 years after declaring it eradicated in 1966. To further reduce the risk of NWS returning, the program expanded south through Central America in the 1990s and 2000s.
Today, in addition to 4 million sterile flies per week already being released in the border region, USDA is “expediting” extra releases through ground chambers inside the infested zone and aerial drops just outside it. USDA has turned on the sterile‑fly dispersal facility at Moore Air Base in Edinburg, Texas. Longer-term, the agency is working with the Army Corps of Engineers on a new domestic production facility in southern Texas designed to eventually deliver up to 300 million sterile flies per week, plus upgraded dispersal infrastructure and aircraft capacity.
Still, sterile fly supply is contained and scaling production will take time, something livestock stakeholders worry that the industry does not have. The biggest concern is that the flies will have time to spread and become more entrenched before the USDA produces the flies in large enough quantities to manage the outbreak.
Colossal Bioscience has an idea to utilize more modern technology. Their proposal includes making a single edit to the fly’s genome that will make females infertile. Engineers insert a self-replicating CRISPR gene, known as a “gene drive,” into the screwworm genome, targeting genes essential for female fertility. Over successive generations, more female offspring are infertile. Because screwworm females typically mate once in their lifetime, each mating with a drive‑carrying male has an outsized impact on future population growth.
As the frequency of infertile females rises, the local screwworm population is expected to crash, potentially to the point of elimination within a defined region. Colossal refers to this as a “genetic biocontrol” strategy: using the target species’ own reproductive biology as the lever instead of insecticides or radiation. Critics of gene drive
In practice, a Colossal‑style program would look familiar in some ways to the existing sterile‑insect system. It still requires facilities to rear large numbers of flies and an aerial or ground‑based release program. The key differences are what is released and what happens afterward.
Because the drive spreads from one generation to the next, the number of engineered insects released can, in theory, be lower than in SIT while still achieving population collapse. Once the drive has swept through the population and the local screwworm population has crashed, ongoing releases might not be needed, at least in that geographic area.
Supporters argue that this self‑propagating feature is what makes gene drives attractive, as upfront development and regulatory costs could yield long‑lasting suppression without perpetual large‑scale releases. However, the pathway from lab concept to ranch‑level impact is uncertain and will depend on regulation, public acceptance, and technical performance. As of now, gene drives for agricultural pests are still in experimental and contained‑trial stages, and no country has approved an agricultural gene drive for wide release. (Sources: USDA APHIS, Dallas Morning News, Fortune, Colossal)
