Screwworm comeback
Screwworms were once endemic to the US, but were eradicated in the 1960s amid a concerted effort to annihilate their population. This is done with aerial bombings of sterile male flies, which is the most effective weapon against the parasites. The mass release of dud studs elbows out fertile males, preventing them from mating with females, which generally only mate once.
With this method, called Sterile Insect Technique, the flies were eradicated not just from the US, but from all of Central America. They were declared eradicated from Panama in 2006.
Until recently, the screwworm population was kept at bay via a biological barrier along the Darién Gap at the border of Panama and Colombia. The USDA partnered with authorities in Panama to build a sterile fly production facility at the gap to regularly release sterile flies and hold the line. But in 2022, the barrier was breached, and the flies have been relentlessly buzzing northward since.
In response, the US has expanded surveillance and trapping efforts in Texas. It is also constructing a $750 million sterile fly production facility in South Texas. USDA says it is currently dispersing 100 million sterile insects per week in Mexico and along the US-Mexico border to prevent the flies from advancing further.
In the press release Wednesday night, the USDA said it will be releasing sterile flies via ground release chambers in the area around the detection. That’s in addition to the 4 million flies already being released in the area by air this week.
“The United States has defeated this pest before, and we will do it again,” Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs at the USDA said in the press release.
This post was updated at 10:45 pm ET to reflect that the USDA confirmed an infection of NW screwworm.
