CNN
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Thousands of millions of fly flies falling from airplanes may sound like a horrifying nightmare, but experts say such a flock could be the livestock industry’s best defense against the carnivorous threat poised to invade the US southwestern border.
New World Screwworm Outbreaks – The form of a species of fly larvae known to nest and eat slowly in the wounds of warm-blooded animals has spread across Central America since early 2023, with invasions recorded in Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize and El Salvador. Most Central America countries have not seen an outbreak in 20 years.
The fly reached southern Mexico in November, causing concern among US agricultural industry officials, causing the closure of cattle, horse and bison trading ports in several border areas.
It was not the first time the US had to fight these invasive bugs. The country largely eradicated New World screwworm populations by breeding sterile male species in the 1960s and 1970s, dispersing them from planes and mating with wild female fly.
The strategy essentially fights flies with flies – slowly degrades insect populations by preventing more eggs from laying. Now, as insects continue to spread, Northern officials hope that the approach will work again.
But today, only one facility in Panama breeds New World screwworms sterilized for dispersion, and according to a June 17 letter from 80 US lawmakers, hundreds of millions of sterile flies are needed to slow the outbreak.
The next day, the USDA announced plans to open a “Fly Factory” in a town that has not yet been decided near the Texas-Mexico border. However, the process of killing a screw worm may not be quick.
New World Screwworms are parasitic larvae of metallic blue blowfly A species called Cochliomyia hominivorax. Dr. Philip Kaufman, professor and director of the Department of Entomology at Texas A&M University, unlike all other blowflies native to the Western Hemisphere, New World Screwworms feed the meat of live animals rather than dead animals.
Carnivorous maggots go for most warm-blooded animals, including horses and cows.
They are also known to infect household pets and humans in rare cases, Kaufman said.
“After mating, the female fly finds a living host, lands on the wound, lays up to 200-300 eggs,” Kaufmann explained. “After 12-24 hours, all those eggs will hatch and soon begin to burrow into the animal’s tissue, creating a very large wound.”
After the larvae eat tissue with sharp mouth hooks for several days, they fall to the ground and appear later, according to Thomas Lansford, the Associate Executive Director and Assistant State Veterinarian of the Texas Animal Health Board.
Since the outbreak began in 2023, statistics registered with the Panama -United States Commission Committee have reported invasions of over 35,000 New World Screwworms, according to statistics listed in the Eradication and Prevention Committee on the Livestock (COPEG) website. In such cases, cattle account for about 83% of the affected animal species.
Treatment of invaded cows often includes washing, preservative treatment and wound covering, Lansford said.
If left untreated, the fly will kill the animal within a week or two, spreading it to others, pose a threat to the rancher’s livelihood.
“They’re the first to be able to live in,” said Stephen Diebel, rancher and first vice president of the Texas and Southwestern Cow Razors Association. “We know the incredible economic impacts that intrusions cause.”
According to Diebel, there are no known vaccinations or effective repellent methods to prevent invasion. Instead, he recommended that during warm months, ranchers should avoid branding, tagging and other procedures that create potential entry points for domesticated screwworms. Tropical flies are less active in the winter.
While local cattle trade is considered to be the main way fly populations move, Diebel says invasions can also affect wildlife such as deer, birds and rodents, making monitoring of parasite spread even more challenging.
Just as the caterpillar enters coco before it becomes a butterfly, the new world’s screwworm becomes a black pill-sized tobacco before it appears as an adult fly, Kaufman explained.
According to the USDA, in sterile fly production facilities, co receives high-energy gamma rays that destroy male DNA, causing damage to sex chromosomes. The result: helpless adult fly to lay eggs that are not immersed in female companions.
According to the USDA, the amount of radiation exposed to male fly is not poses a danger to animals or humans. However, women mate only once with a short 20-day life expectancy when the population is exposed to infertile men, so depending on the size of their departure, the population disappears over a few months or years.
It is unclear how dispersion will work in the US if it occurs, but Kaufman said adult flies are usually loaded into temperature-controlled vessels and dropped from the plane. But you don’t need to panic about flydrops coming to your nearby suburbs, he said – they are usually not interested in urban environments, so they target sparsely populated rural areas.
The Copeg facility produces about 100 million sterile flies each week and is dispersed in the air.
Currently, according to Copeg’s website, dispersal efforts are focused across Mexico’s southern region and Central America.
The new US dispersed facility is located at Moore Air Force Base in Hidalgo County, Texas, and is expected to cost $8.5 million per release. The location and price tag of the production facility, or the “fly factory” itself, have not been revealed, but lawmakers estimate it will cost around $300 million.
In addition to the new sterilized fly facility, the USDA has also announced a $21 million plan to renovate an old Mexican fly factory by the end of 2025.
The plan is expensive, but it’s a price worth paying to save the billion-dollar livestock industry, Diebel said.
“It’s a simple trade-off to understand that these fly offset $300 million in economic impacts,” Diebel said.
Shortly after its June 18th announcement, the USDA shared plans to begin reopening livestock trading ports in Arizona, Texas and New Mexico, which were closed last year, citing surveillance across Mexico and dispersing sterile fly.
Copeg did not immediately respond to a request for comment on details regarding current progress in the US distributed initiative.
