Parasitic Fly Will Return To Texas

A parasitic fly, responsible for a pest in Texas during the 1960s, is creeping back, and ranchers and wildlife scientists are sounding alarms. The New World screwworm lays its larvae in open wounds of live mammals, where they “burrow into the wound to feed on the living flesh”, according to the U.S. Centers for Disease Control And Prevention (CDC). These wounds can become fatal if left untreated.

Although the flies were pushed south and out of Texas by the 1970s, in recent years they’ve headed north again. Mexico’s ministry of agriculture released a statement on Monday, reporting a new case of New World screwworm in Sabinas Hidalgo, Nuevo León, less than 70 miles from the border of Mexico and the United States.

Risks to Wildlife and Livestock

While cattle have historically been the focus, wildlife may suffer too. As Marcus Blum, Texas A&M wildlife specialist, said to the Texas Standard: “The most obvious … is going to be white‑tailed deer. But…it’s any warm‑blooded animal, although mammals seem to be the particular focus of this parasite.” 

Blum mentioned the economic stakes are also high: “Just the white‑tailed deer industry alone in Texas is valued at over $9 billion.” 

If populations decline, losses “could be millions, even billions of dollars,” Blum declared. Diseases like this amplify the challenges wildlife already face from habitat fragmentation and increasing development.

Prevention and Preparation

Experts do not assume the fly’s arrival is inevitable. As Blum explains: “USDA and Mexico are working really hard, and other groups are working diligently, to keep the fly from continuing to spread north. So at this point, we’re not assuming that it’s going to get here.”

Governor Greg Abbott has directed the Texas Animal Health Commission and Texas Parks & Wildlife to form a joint New World Screwworm Response Team to coordinate efforts. Meanwhile, agencies stress early detection and reporting as critical:

“If you see LIVE animals with LIVE maggots, report the sighting to your local TPWD wildlife biologist. Early detection is key,” Texas Parks and Wildlife.