A flesh-eating parasite A fly that is a major threat to livestock has returned to the United States after 60 years. This week, the United States Department of Agriculture confirmed presence of New World screwdriver in south Texas calves.
It was removed from the United States in 1966 and as far south as Panama by 2006, it is recent to emerge again in Mexico made it possible that the screwdriver would finally enter the country again, with the model showing that it could arrive as soon as summer 2025. It took a little longer, but the screwdriver has arrived. And to end the outbreak, officials are using a tried and true method: releasing large numbers of adult maggot flies.
Ringworm infection occurs when the female fly lays her eggs on open wounds or other body parts of warm-blooded animals. When the eggs hatch, maggots emerge and eat living tissue before turning into flies. As adults, maggot flies do not bite or feed on flesh. Scientists in the 1930s and 1940s thought that if they could prevent female flies from reproducing, they could break the cycle. At that time, New World tapeworms killed hundreds of thousands of cattle each year, mainly in the American South and Southwest.
In the 1950s, researchers at the USDA made a breakthrough when they irradiated cockroaches and made them sterile. When released into an infected area, the sterile males mate with wild female insects and produce inviolable eggs. No children are produced, and the population falls. It is known that the pest control method was successfully used for the first time on the island of Curacao, off the coast of Venezuela. It took just seven weeks to eradicate the pests, and the effort saved the island’s goat herds, which were an important source of food.
The technique takes advantage of the fact that female New World woodpeckers mate only once in their lifetime. “The sterile insect method is probably the most eloquent example of a completely successful biological control method,” says Sally DeNotta, associate professor of veterinary medicine at the University of Florida. “The cycle of life stops. No generation is produced. It has been very successful.”
For many years, a dense area of rainforest between Panama and Colombia known as the Darién Gap served as a biological barrier where destructive flies were released to prevent the caterpillars from spreading north. But insects began to break the barrier in 2022.
To contain the outbreak in South Texas, the USDA has cordoned off an approximately 12-mile zone around the infected calf and is implementing a targeted release of the pest flies from trucks. That’s in addition to the 4 million unborn flies each week that are already being released into the air in the area. Anticipating the movement of the screwdriver in the north, in February, agency transferred its effort to disperse 100 million sterile flies per week to target the area along the US-Mexico border.
“While this development is a serious threat to our livestock and wildlife, we are not alarmed,” USDA Secretary Brooke Rollins said during a House Agriculture Committee hearing. the meeting on Thursday.
He said about 400 million flies a week are needed to deal with the worms. Currently, the United States can only produce about 100 million flies per week station in Panama.
A sterile insect facility in Mexico was closed in 2012, but the USDA is closed invest 21 million dollars to help renovate and convert an existing fly facility in Metapa, Mexico, to produce an additional 60 to 100 million sterile flies per week. The facility is expected to be operational this summer, according to the USDA.
