Two of Texas’s most troublesome invasive species have much in common. They reproduce alarmingly fast, send shudders down the spines of Texas ranchers, and can traverse similar distances (about twelve miles a day). One is the feral hog, capable of outsmarting, outrunning, and outbreeding attempts at its eradication. The other, if presented a pinprick-size opportunity, would eat a live feral hog from the inside out.
The New World screwworm recently returned to Texas, sixty years after the state first fended off the orange-eyed threat. More than thirty cases have been recorded since the confirmed infection of a calf in tiny La Pryor last month. The flying pest inflicts otherworldly horror. It lays its eggs in wounds as tiny as those created by tick bites, and its larvae burrow into and feast on the surrounding flesh.
Any warm-blooded animal is vulnerable, but the screwworm is especially worrisome to cattle ranchers. An infestation can devastate a herd, spreading quickly among animals that share close quarters. If a screwworm infection is left untreated, an adult bovine can succumb in under a week. Fighting screwworm is labor-intensive, requires thorough observation and treatment, as well as the quarantining of sick livestock. This can cause supply chain issues and eventually drive up the cost of your steak dinner.
Meanwhile, Texas has turned into a real pigsty. Our state is home to more feral hogs than any other, and experts estimate that more than half of the country’s entire wild-pig population resides in Texas. John Tomeček, a Texas A&M associate professor of wildlife sciences, pegs the statewide number at between 3.5 million and 6 million. “Those are conservative estimates,” he said. “To give you context, we’re fairly certain there are more pigs in Texas than there are white-tailed deer.”
Feral hogs cause hundreds of millions of dollars in damage throughout the state each year. Traveling in groups called sounders, they’re known for destructive rooting, using their snouts to pillage rows of crops in search of food, often outcompeting native species in their hunt for edible plants and acorns. They also cause substantial damage to fences, farm equipment, and irrigation systems, leaving a path of disrepair in their wake.
Could one wildlife problem solve another, with screwworms acting as a natural population check on feral hogs? Possibly. Tomeček said experts speculate that hog numbers have shot up in recent decades in part because there were no longer any screwworms around.
“It’s going to kill pigs, but at what cost? I don’t want to live in a world where screwworms are so widespread that they’re making a landscape-level dent in the feral-hog population,” Tomeček said. “I think if we get to that point, we’ve got an awful lot of problems we’re managing. We may move more screwworms around than kill pigs.”
There’s no real answer to the question, and we’re probably better off not finding out. Get back to developing the anti-screwworm mitigations, as well as the hog mitigation strategies, and hope for the best.