The U.S. Department of Agriculture has developed NovoFly, an all-male screwworm strain designed to improve the efficiency of a pest control program, according to researchers at the agency's Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas.
The screwworm has resurged in New Mexico and Texas in recent years, threatening livestock and wildlife. The USDA uses the Sterile Insect Technique (SIT), a decades-old method that involves releasing sterilized male flies that mate with wild females, preventing reproduction. When eggs fail to hatch, the screwworm population eventually collapses.
"Releasing sterile screwworm flies is a proven, decades-old approach to eliminating populations of this pest and preventing the harm it inflicts—physically to livestock animals and wildlife and financially to the producers who raise livestock," said Kim Lohmeyer, director of the laboratory.
The new strain addresses a key inefficiency in the SIT program. Historically, producers have had to rear both male and female flies and then separate them before release, since only sterile males are useful for population control. NovoFly was engineered with a genetic mechanism that kills female larvae during early rearing but leaves males unaffected. This allows facilities to rear roughly twice as many males for release using the same resources.
According to the USDA, the SIT technique originated from research by entomologists Edward B. Knipling and Raymond C. Bushland beginning in the mid-1930s. Their work led to the eradication of screwworms in the United States by 1966. In January 2026, USDA Secretary Brooke Rollins announced a New World Screwworm Grand Challenge to counter recent resurgences of the pest through Central America, identifying SIT as a key strategy.
NovoFly is currently undergoing regulatory approval before the Environmental Protection Agency. Once approved, it will be deployed at designated screwworm rearing facilities.