Another Devastating Invasion From Our Southern Border Looming

It’s been decades since the New World Screwworm was a problem in the U.S., but the flies are now advancing northward from Panama. They could disrupt American agriculture if they gain a foothold here again. The U.S. Department of Agriculture recently suspended imports of cattle from Mexico, after new reports showed that a destructive pest called the New World Screwworm had moved north to the Mexican states of Oaxaca and Veracruz.
The New World Screwworm, which is actually a fly, was a huge problem for U.S. livestock and wildlife until it was eradicated in the 1960s. The USDA estimates that livestock producers in the southwestern U.S. lost between $50 million and $100 million annually due to NWS in the 1950s and 1960s until it was successfully eradicated.
While the USDA eradicated NWS in the US 1966, there was an outbreak contained within the Florida Keys in 2016. It affected only in the endangered deer population and was eradicated by March 2017, per APHIS.
Their screw-shaped larvae burrow into mammals’ wounds and other sensitive spots of mammals, like an umbilical cord, causing disease, infection and death.
“This is a critter that we don't want back in the U.S.,” said David Anderson, a livestock professor and extension economist with Texas A&M University. “If you have livestock, you're going to be out there all the time checking your animals for any wound. … I think it would be a pretty devastating thing if we were to get it back.”
The NWS is a fly that is endemic in Cuba, Haiti, the Dominican Republic and some South American countries, according to the USDA's Animal and Plant Health Inspection Service (APHIS).
In rare cases, the larvae can feed on people, the Centers for Disease Control and Prevention states. "People who travel to these areas, spend time among livestock animals, sleep outdoors and have an open wound are at greater risk of becoming infested with NWS," says the CDC.