The US Department of Agriculture recently announced a plan to combat the threat posed by flesh-eating parasitic insects by releasing billions of sterile screwworm flies.
On June 18th, the USDA stated in a release that Agriculture Secretary Brooke Rollins initiated the production facilities for sterile New World Screwworm (NWS) flies in southern Texas to address the threat posed by flesh-eating parasitic insects.
The statement highlighted that the flesh-eating larvae of the New World Screwworm flies are a destructive parasitic insect causing severe and often fatal damage to livestock, wildlife, and pets, with rare cases also posing a threat to humans. These flies are expected to reach the US border by the end of this summer.
Female New World Screwworm flies lay their eggs on wounds or orifices of warm-blooded animals. Once the eggs hatch into larvae, they feed on flesh, worsening the wound continuously and potentially leading to the death of the host.
A single female New World Screwworm fly can lay up to 3,000 eggs in its lifetime. Therefore, this parasite poses a significant threat to livestock, wildlife, and pets.
According to a USDA document from April this year, the Sterile Insect Technique (SIT) was developed in the 1950s to eradicate New World Screwworm flies in the US, Mexico, and Central America.
This technique involves irradiating the fly pupae with gamma radiation, causing the male flies to become sterile.
When these sterile male flies are released in large numbers, they mate with wild female flies, leading to the production of unfertilized eggs and thus eradicating the pests.
The statement also mentioned, “Although the New World Screwworm flies were eradicated from the US decades ago, they were recently discovered in Oaxaca and Veracruz in Mexico, only about 700 miles from the US border. As a result, the US suspended the import of live cattle, horses, and bison from southern border ports on May 11th.”
The sterile screwworm fly production facility at Moore Air Force Base in southern Texas was launched by Agriculture Secretary Rollins at a cost of $8.5 million.
Currently, the US purchases 100 million flies per week from a sterile screwworm fly production facility in Panama. The USDA has invested $21 million in constructing new production facilities in Mexico, which, when operational, could provide an additional 60 to 100 million sterile screwworm flies per week.
“We have defeated NWS before, and we will defeat it again,” Agriculture Secretary Rollins stated. “We will not ignore the threat NWS poses to our livestock industry, economy, and food supply chain.”
In a statement on June 18th, the National Cattlemen’s Beef Association (NCBA) expressed strong support for the USDA’s initiative.
In their statement, the association said, “To establish an effective barrier in the southern border of the US, we need over 300 million sterile screwworm flies per week. During the peak of screwworm eradication in the 1960s, the US released 400 to 500 million sterile screwworm flies per week.”
Moore Air Force Base is an ideal location for sterile screwworm fly production as it is close to the border, making it easier to rapidly deploy the flies to the areas most severely affected by pests.
On June 19th, Mexico’s Agriculture Secretary Julio Berdegue posted on social media platform X, stating that the US’s actions to strengthen the fight against NWS are “a positive step and, in many ways, will enhance the joint efforts between the US and Mexico.”
He expressed hope that Mexico can soon resume exporting live cattle to the US.
According to a USDA document from January 2025, during the NWS infestation in 1976, Texas alone had 1,488,256 infected cattle, 332,600 infected sheep, and goats.
(Adapted from an Associated Press report)