Fly vs Fly: Millions of flies will rain down from planes on America. And no, it's not a biological weapon attack

In the US, millions of flies will be dropped from planes. No, it's not a biological weapon. It's a method to fight the spread of New World screwworms, a parasitic flesh-eating larva of the Cochliomyia hominivorax fly species. Once eradicated from the US, these flies are spreading again in the US, having come from Latin America. And scientists and lawmakers are worried about millions of dollars of damage the flies can cause to livestock industry. The way out? Airdropping more of these flies. Doesn't make sense? Read on:

How deadly are the New World Screworms?

The larvae of New World Screwworm flies can infest wounds in warm-blooded animals like cattle, horses, pets, and even humans. The medical term for infestation of an animal by a maggot is myiasis. Once the flies lay eggs on open wounds of animals, the maggots will 'slowly eat them alive,' said Dr Phillip Kaufman of Texas A&M University in a report on CNN.

New World screwworm infections have been spreading in Americas

The New World screwworms have been spreading in an outbreak that started in early 2023. It started from Latin America, winding through Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize and El Salvador. It reached southern Mexico in November, and is slowly affecting animals across the US border in Texas.

The Panama–United States Commission for the Eradication and Prevention of Screwworm Infestation in Livestock, or COPEG, listed more than 35,000 New World screwworm infestations, 83 per cent of which were on cows.

Screworms were eradicated in the US, but coming back

The flies vs flies method was used for the first time by the US in the 1960s and 1970s to eradicate screwworms. This eventually helped reduce the population of srewworms and eradicate them.

In june, 80 US lawmakers warned in a letter that hundreds of millions of more sterile flies are needed to fight the New World screwworms.

The USDA, the country's drug regulator, announced plans to open a US fly factory near the Texas-Mexico border and renovate an old facility in Mexico, said the CNN report.

How are the sterile flies produced?

The mass-production of sterile male flies is done by sending gamma rays to the pupae to make them impotent. These flies are not harmful to humans or animals. The sterilised male flies are dispersed to mate with wild females, who then lay unfertilised eggs. “The female fly finds a living host, lands on its wound, and will lay up to 200 to 300 eggs... they immediately start burrowing and feeding on the tissue.” Kauffman told CNN.

The dispersal of these impotent male flies is done trhough temperature-controlled containers from planes, targeting rural areas, said the CNN report.

The COPEG facility currently produces about 100 million sterile flies weekly.

The fly vs fly plan will cost millions

The US facility for mass production of sterile flies will be located at Moore Air Base in Hidalgo County, Texas. This will cost $8.5 million even as lawmakers estimate the overall fly factory project at around $300 million. The USDA, meanwhile, is investing around $21 million to upgrade the Mexican plant by late 2025, said the report.