Texas Gov. Greg Abbott to give update on state's flesh-eating screwworm response
Texas state officials are set to update Gov. Greg Abbott on efforts to control the New World screwworm (NWS) fly after the flesh-eating parasite was found in the state.
The U.S. Department of Agriculture confirmed on Wednesday that it was discovered in a 3-week-old calf in Zavala County, between San Antonio and Eagle Pass in South Texas. The calf is the only affected animal so far.
The USDA said it was taking immediate action to eradicate the parasitic fly by establishing a 12-mile "infested zone" around the detection site and implementing quarantines, increasing traps for screwworms along the border and establishing an Incident Command Team with the Texas Animal Health Commission.
The week before Wednesday's announcement, the USDA had said the screwworm was detected in Mexico just 25 miles from the U.S. border. That encounter had been the closest to U.S. soil since at least last September, federal data shows, before the confirmed case in Zavala County.
Efforts to stop the spread of New World Screwworm flies
State and federal officials have been tracking the screwworm fly for more than a year as it has made its way northward through Mexico.
The Texas Parks and Wildlife Department first issued a warning over the screwworms in January of 2025. Since then, the state and federal governments have taken multiple steps to prevent the NWS flies from spreading and protect American agriculture.
The U.S. Department of Agriculture built an $8.5 million facility at Moore Air Base in the Rio Grande Valley to breed millions of sterile male NWS flies, then release them into the wild to mate with females and prevent them from laying eggs. The federal government also temporarily suspended imports of live cattle, horses and bison from Mexico.
The Texas Department of Agriculture deployed traps along the border last summer loaded with a synthetic bait that mimics the smell of rotting animal flesh to attract, trap and kill the flies. Texas Agriculture Commissioner Sid Miller estimated last year that the traps would eradicate up to 90 percent of NWS flies.
In January, Abbott issued a disaster declaration to help bolster the state's efforts to combat the threat.
Worms are a threat to American livestock
The U.S. Department of Agriculture calls the New World Screwworm a "devastating pest."
"When NWS fly larvae (maggots) burrow into the flesh of a living animal, they cause serious, often deadly damage to the animal," the USDA said. "NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people."
The Texas Parks and Wildlife Department says the maggots will lay eggs in "open wounds or orifices of live tissue such as nostrils, eyes, or mouth."
"These eggs hatch into dangerous parasitic larvae, and the maggots burrow or screw into flesh with sharp mouth hooks. Wounds can become larger, and an infestation can often cause serious, deadly damage or death to the infected animal."
The worms can also affect humans, although cases are rare. Last year, the Department of Health and Human Services announced the first case of an NWS infestation in a human was confirmed in the U.S. after a traveler returned to Maryland from El Salvador. Maryland health officials later said the person had recovered, and investigators did not find evidence of transmission to other people or animals.
