Airborne Flies Deployed to Combat Flesh-Eating Screwworms

The United States government is undertaking an unusual operation of releasing billions of flies from aircraft over Mexico and southern Texas to combat a dangerous parasite.

This initiative, although it resembles a scene from a horror film, is a strategic response to neutralize a pest that threatens the beef industry, wildlife, and domestic animals. Previously successful, this approach is scientifically validated.

Government Strategy Against Screwworm Infestation

Edwin Burgess, a University of Florida professor with expertise in animal parasites, endorses the science behind this method, highlighting its effectiveness in addressing large-scale challenges.

The target of this initiative is the screwworm larva. The USDA plans to increase production of sterilized male flies, which will then be released to mate in the wild. The mating results in non-viable eggs, thus gradually reducing the fly population.

This technique offers a more environmentally sustainable solution compared to chemical spraying and was instrumental in eliminating the pest in past years across regions north of Panama.

Implementing Strategic Breeding and Release

By July 2026, the USDA plans to launch a new fly production facility in southern Mexico, complemented by a distribution hub in southern Texas. These hubs will facilitate the import and dispersion of flies if required.

The scientific terminology for this pest is Cochliomyia hominivorax, meaning "man-eater," aptly describing the screwworm's destructive potential.

Screwworm larvae inflict severe injuries on living animals by burrowing into their flesh, posing serious threats not only to livestock but also to pets, wildlife, and occasionally even humans.

Impact on the Beef Industry

Unlike typical larvae that consume decaying matter, New World screwworm flies, and their relatives in Asia and Africa attack living tissues, posing a grave risk to the American cattle industry.

As emphasized by Michael Bailey from the American Veterinary Medicine Association, an afflicted cow could die within two weeks.

Veterinary interventions exist but dealing with such infestations can severely distress and pain the affected animals.

Leveraging Biological Characteristics

Previously considered a seasonal pest, the New World screwworm can't withstand colder U.S. climates. However, past efforts utilized over 94 billion sterile flies to eradicate the pest from 1962 to 1975.

For optimal effectiveness, sterile males must be present in high enough numbers to ensure interaction with wild females.

Notably, screwworm females mate only once during their short lifespan, a crucial factor in controlling their population.

Reasons to Expand Fly Production

The U.S. responded to the screwworm's northern advance by halting livestock imports at the southern border, a situation that remains until at least mid-September.

Given the pest's ability to target any warm-blooded species, including humans, the urgency to manage its spread is evident.

America initially closed fly production facilities in Florida and Texas after declaring the pest eradicated. Now, efforts focus on revamping capacity to breed at least 400 million flies per week.

Mass Fly Raising Techniques

Raising substantial fly numbers involves understanding and catering to their breeding needs, as explained by Cassandra Olds of Kansas State University.

Through historical adjustments, fly factories have evolved their feeding processes, utilizing diverse nutrient mixtures to nurture larvae into adulthood.

Security of these facilities is robust, ensuring no escape of fertile flies to avert additional infestations.

Challenges of Aerial Fly Deployment

Aerial fly release, while crucial, is not without danger, as illustrated by a recent crash during such an operation resulting in casualties.

Over the years, fly dissemination methods have refined from basic containers to advanced mechanical systems.

The USDA's historical achievements in pest control underscore the need for proactive management of facilities to prevent resurgence.

Continuing vigilance is necessary, as threats thought to be resolved can—and often do—reemerge.