US to Create Army of Hundreds of Millions of Flies for "Fighting" on the Border

Liputan6.com, Jakarta Hundreds of millions of flies dropped from airplanes in the sky may sound like a scary scenario.

However, to experts, it's one of the most important strategies for protecting the US livestock industry from a serious threat.

Since early 2023, a New World screwworm outbreak has been spreading across Central America, including Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize, and El Salvador. Most of these countries had not experienced it before in the last 20 years.

At its peak, in November 2024, the flesh-eating parasite was detected in southern Mexico.

This sparked serious concern among US agriculture officials, resulting in the closure of several border trading ports for cattle, horses, and bison.

This is not the first time the US has faced an invasive insect infestation. In the 1960s and 1970s, the screw worm was successfully eradicated using a unique technique: breeding sterile male flies that were dispersed by airplane.

The goal was for the male flies to mate with wild females without producing eggs, resulting in a slow decline of the population.

Now, as the outbreak nears the border, officials hope this method will work again.

However, there is a significant challenge: Currently, there is only one sterile fly breeding facility in Panama, with hundreds of millions of additional flies required.

According to a June 17 letter from 80 US lawmakers, the effort is urgent to slow the spread.

The next day, the US Department of Agriculture (USDA) announced plans to build a new sterile fly factory near the Texas-Mexico border.

Cochliomyia hominivorax, a metallic bluish-green fly, is the culprit of this outbreak. Its larvae, known as New World screw worms, attack warm-blooded animals, from cattle and horses to pets and even humans in rare cases.

"After mating, the female flies settle on the animal's open wounds, then lay 200-300 eggs," explained Dr. Phillip Kaufman, professor of entomology at Texas A&M University, as quoted from CNN, Thursday (10/7/2025).

"Within 12-24 hours, the eggs hatch. The larvae immediately burrow into the tissue and cause large wounds."

Thomas Lansford, Deputy Executive Director of the Texas Animal Health Commission, added that the larvae then fall to the ground to turn into adult flies.

Without treatments such as wound cleansing, antiseptics, and wound closure, these infestations (characterized by large numbers of parasites attacking the host) can kill animals within one to two weeks.

Since 2023, according to the COPEG Commission, there have been more than 35,000 cases of infestation, with cattle being the main victims (83 percent).

"Every day we have to check cattle for infestation," says Stephen Diebel, rancher and Vice President of the Texas & Southwestern Cattlemen's Association. "The economic impact can be tremendous."

There is no vaccine or specific preventative medicine. Ranchers are advised to avoid procedures such as stamping or tagging during the infestation-prone summer season.

In sterile fly factories, fly pupae are exposed to high-energy gamma irradiation that damages the DNA of males so that they are unable to fertilize females.

"Because female flies only mate once in their short lives, populations can be wiped out in a matter of months or years, depending on how widespread the outbreak is," says Kaufman.

Typically, sterile adult flies are packaged in temperature-controlled containers and dropped from airplanes in sparsely populated rural areas.

Kaufman emphasized that people do not need to worry about these flies spreading in urban areas.

The COPEG facility in Panama currently produces approximately 100 million sterile flies per week, which are distributed to the affected areas.

The USDA plans to build a new US$8.5 million facility at Moore Air Base in Hidalgo County, Texas.

Meanwhile, the construction of a sterile fly breeding plant in the US is estimated to cost up to US$300 million. Not only that, the USDA has also allocated US$21 million to renovate an existing facility in Mexico by the end of 2025.

"When compared to the potential industry losses of US$300 million to US$10 billion, this investment is clearly important," Diebel said. "An in-country facility will make it easier to control the distribution of sterile flies."

On June 18, the USDA announced plans to reopen previously closed livestock ports in Arizona, Texas, and New Mexico, following positive developments in the surveillance of the outbreak in Mexico.

As of press time, COPEG has yet to make a statement regarding the latest developments in this initiative.