U.S. Deploys Sterile Flies to Fight Screwworm in Panama

Panama City, Panama — In an unprecedented operation, the United States has begun releasing approximately 14 million live flies weekly over Panama’s jungles. While the mass release of insects may appear alarming at first glance, the initiative is a strategic effort to combat a dangerous pest threatening both animal and human health across Central America.

A Biological Defense Against a Deadly Pest

The target of the operation is Cochliomyia hominivorax, commonly known as the New World screwworm fly. Its larvae infest the living tissue of animals and humans, causing severe infections and, in extreme cases, death. The U.S. intervention, conducted with the approval of the Panamanian government, aims to establish a biological barrier in the narrow isthmus of Panama, preventing the pest’s northward spread.

According to data from the Panama-United States Commission for the Eradication and Prevention of Screwworms (COPEG), 15,638 cases were recorded in both countries by the end of 2024. The infestation has rapidly advanced in North America in 2025, endangering livestock and rural communities while posing risks to food security and economic stability.

The Sterile Insect Technique

The operation employs the Sterile Insect Technique (SIT), a biotechnological method involving the mass breeding of male screwworm flies in specialized laboratories. These flies are sterilized through controlled radiation before being released into the wild.

When sterile males mate with wild females, the resulting eggs are nonviable, gradually reducing the pest population. While SIT has been used previously in the U.S., its deployment in Panama marks a critical expansion, leveraging the country’s geographic position as a natural containment point between North and South America.

A Continental Shield Against Economic and Health Risks

The screwworm fly’s larvae cause deep wounds and infections in livestock, leading to significant agricultural losses. Human cases, though rarer, have also been documented, elevating public health concerns.

The weekly releases are part of a broader zoosanitary strategy to protect the Western Hemisphere’s livestock industry. Panama, supported by U.S. logistical and technological resources, now serves as a frontline defense against the pest’s spread.

This joint effort underscores the urgency of preventing further outbreaks, safeguarding both regional economies and public health. The operation reflects a long-term commitment to biological pest control, aiming to eradicate Cochliomyia hominivorax and stabilize the affected ecosystems.