The United States and Mexico have agreed to intensify their fight against the New World screwworm fly, a dangerous parasite that threatens livestock across North America and could devastate the U.S. cattle industry if left unchecked.
At a Glance
- Mexico has agreed to allow U.S. sterile fly planes to land as part of eradication efforts after pressure from Agriculture Secretary Brooke Rollins
- The USDA has allocated $165 million in emergency funding to prevent the parasite from reaching the U.S. border
- New World screwworm flies lay eggs in open wounds, causing severe tissue damage that can be fatal if untreated
- The parasite was eradicated from the U.S. in 1966 but has been spreading northward through Central America since 2022
- Cattle industry groups strongly support the USDA’s actions to hold Mexico accountable in managing the threat
A Dangerous Parasite Returns
New World screwworm, a parasitic fly once eradicated from U.S. soil in 1966, has been steadily marching northward through Central America since an outbreak began in 2022. The pest, which has now reached Mexico, poses a severe threat to American cattle and agriculture. Female screwworm flies lay eggs in open wounds of livestock and other warm-blooded animals, including humans in rare cases. When these eggs hatch, the larvae feed on living tissue, causing devastating damage that can be fatal if left untreated.
The United States Department of Agriculture (USDA) has maintained a biological barrier at the Darién Gap between Colombia and Panama for decades to prevent the pest’s northward migration. However, this defense has been breached, with the parasite now confirmed in Mexican territories, creating an urgent need for coordinated international action. Agricultural officials estimate that if the screwworm reaches the United States, it could cost American producers millions of dollars annually in livestock losses and control measures.
U.S.-Mexico Cooperation Secured
After significant diplomatic pressure, Mexico has agreed to allow U.S. sterile fly planes to land in its territory – a crucial step in the eradication campaign. Secretary of Agriculture Brooke Rollins had threatened to suspend livestock imports from Mexico if the country did not cooperate by April 30. The sterile insect technique, which involves releasing laboratory-bred sterile male flies to mate with wild females, has proven effective in past eradication efforts but requires consistent aerial deployment to succeed.
“Mexico has agreed to let our sterile fly planes land,” confirmed U.S. Agriculture Secretary Brooke Rollins.
Rollins had previously criticized Mexican customs for imposing import duties on supplies needed to combat the pest and delaying critical flights carrying sterile flies. These barriers had allowed the dangerous pests to spread unchecked into southern Mexico. The USDA has allocated $165 million in emergency funding to prevent the screwworm from reaching the U.S. border, demonstrating the seriousness with which American officials view this threat to national agriculture.
Cattle Industry Support
Major livestock organizations have strongly backed Secretary Rollins’ efforts to secure Mexican cooperation. The National Cattlemen’s Beef Association (NCBA), Texas & Southwestern Cattle Raisers Association (TSCRA), and Oklahoma Cattlemen’s Association have all voiced their support for the USDA’s firm stance. These industry groups recognize the potential devastation that could occur if the screwworm reaches U.S. herds after having been absent from American soil for nearly six decades.
While human infection with screwworm flies, known as myiasis, is rare, a recent case was confirmed in Chiapas, Mexico, highlighting the pest’s potential public health implications beyond livestock concerns. The USDA has emphasized that rapid response is essential, as delays in implementation could allow the pest to spread further north, potentially undoing decades of successful eradication work and threatening both agricultural and human health across North America.