From a leaky aluminum boat, hunter, conservationist, and author Jackson Landers scans the swampy shores of Louisiana's Caddo Lake. Cloud cover blots out any stars, making the diffused green glow of Landers' flashlight the only available light. We're hunting nutria – large, invasive, semiaquatic rodents that have wreaked havoc in the Gulf States over the past 70 years – and though our intentions are ecologically correct, we're doing it illegally, haphazardly, and deep in alligator territory.

The nutria resembles the beaver, rat, otter, and muskrat but is actually a distinct species native to South America. Myocastor coypus evolved alongside predators like the jaguar and anaconda, which keep its numbers in check throughout its indigenous habitat. But in Louisiana, it's a scourge, laying waste to precious grasses, extirpating native animals, and undermining the levees and dikes constructed to prevent chunks of the state from being swallowed up by the Gulf of Mexico. So far, no predators here have acquired an appetite for nutria that can keep pace with their prodigious reproduction. That, Landers says, is why we have to.

"It seems incredibly wasteful to eat factory-farmed meat when there are perfectly edible, hormone-free animals roaming around doing unspeakable damage to local ecosystems," says Landers, encapsulating the premise of our adventure and of his recent, rollicking book, 'Eating Aliens.' "Not to mention this meat is completely free of charge."

Nutria have long been eaten by South American tribes. And in Louisiana, they've been consumed by the indigent and the novelty seeking, sometimes appearing on menus under their French name, ragondin. But they were not brought to the U.S. to be eaten.

In the 1930s, when Edward Avery McIlhenny, of the Tabasco sauce McIlhennys, began importing and farming nutria on Avery Island, 100 miles east of New Orleans, a fur-bearing animal with prolific breeding habits seemed an ideal commodity. McIlhenny released large numbers into the bayou, believing that the loosed animals would benefit the local trapping economy and help manage plant growth. Bad idea.

By the late 1950s, there were an estimated 20 million nutria in coastal Louisiana. Their eating habits – each animal can consume 25 percent of its body weight per day and wastes 90 percent of the plants it devours – have caused an incredible amount of damage to the region's riverbanks, levees, and wetlands, hastening the erosion of coastal marshland (a devastating development for a state that has lost more than 2,000 square miles of land to the Gulf since 1932). And the problem isn't limited to Louisiana – or to nutria. Efforts to control invasive plants and animals nationwide cost the U.S. economy an estimated $120 billion a year.

Landers' solution – one he stumbled upon a few years ago, when he went broke and began shooting the deer that roamed his rural Virginia backyard in order to feed his family – is to hunt these species. Black spiny-tailed iguanas, Asian carp, and wild pigs – each of these invasives (and more) has a chapter in his book. His research consisted of traveling to where they're doing the most damage – Florida, Missouri, and Texas, respectively – and, with the help of locals, learning how to make supper of a scourge.

He knows it's a hard sell. "It's definitely a cultural thing," Landers says of people's reluctance to dine on vermin. "What we choose to eat has more to do with what's accepted at the time than what makes sense."

The Nature Conservancy's Kristina Serbesoff-King admires Landers' pluck but cautions that his approach would not be a quick fix. "Eating invasives could help slow their proliferation," she says, "but on its own, it would make only a small dent in the problem."

Landers isn't too discouraged. "Do I think everybody is going to start shooting invasives and filling their freezers? No," says the 34-year-old former insurance broker, whose foray into hunting was entirely self-taught. "I wrote the book to say, 'Invasive species are a man-made problem, one that costs billions of dollars and that, theoretically, we can eat our way out of.'"

That is, if you can actually kill the things. Landers' experience hunting deer, it seems, doesn't readily translate to this new prey. Within minutes of our arrival on Caddo Lake, he identifies the beds of vegetation that nutria build and finds a skull with one of their trademark two-inch-long orange incisors still intact – proof we're in the right place. Then, from his car, he produces two rifles, a Ruger pistol, a snub-nosed revolver, and a 12-gauge shotgun. "I have to come prepared for anything," he explains.

His first attempt results in a near miss from 20 yards. The second time, the nutria slinks away as he moves to shoot. He holds fire on the third try, worried the creature paddling by is a mink. For three stiflingly hot, insect-plagued days and nights, we sit like this in the swamp, stalking "nooters" to no avail. At least half a dozen wander into Landers' sights, but every instance results in disappointment. It's not that he's a bad shot – I'd seen him bull's-eye cans from 50 yards. But with the nutria, something always seems to get in the way.

As the end of my trip draws closer, I find it hard to shake the feeling that Landers' philosophical infatuation with hunting invasive species for food may not be matched by his ability to make it happen. In desperation, I place an ad on Craigslist offering $150 if we can come to somebody's infested property and have Landers take a nutria off their hands.

Two fruitless days later, after I part ways with Landers and head to the airport, I get a call from one Ray Nehlig in St. Bernard Parish. His wife had seen my Hail Mary post. I decide to gun it to Ray's to see the hypothesis of Landers' book proved.

Arriving at a street of single-level and mobile homes, I see a white-haired, round-headed man of about 50 holding three cat-size rodents by the tail in his left hand, a vintage .22 in his right.

"Are you Ray?" I shout.

"Yup," he says without looking up.

A younger man lies on his belly in a ditch, shining a flashlight into a burrow.

"Dees is jus baby ones," says Nehlig. "Dere's a big mama in dere. We gon' git 'er."

He lays the nutria down. The animal's long-fingered, leathery forepaws look shockingly human in stark contrast with its webbed hind feet. Its fur is as coarse as the hair on a coconut, its tail almost lizardlike, and its four long, bloodied, orange incisors look like something from a nightmare.

"OK," says Nehlig. "Less clean 'em up."

The quartered nutria go into a pressure cooker, along with water, potatoes, and seasonings. The meat is tasty, but on these three juveniles, there are more bones and guts than flesh. Still, as the ethical-meat movement gains momentum, it does make for a meal I can feel good about.

Landers, for his part, also finally made a kill that day. Three Cajun gentlemen took him hunting on their airboats, from which he cleanly dispatched two adult specimens with his .22. Then local chef Philippe Parola showed him how to dress and cook the animals. (In the late 1990s, Parola led a campaign to market nutria as a lean, healthy protein source, but public perception of the creature as nothing more than an overgrown rat killed the initiative in its tracks. He's since moved on to Asian carp, trying to rebrand it as "silverfin." His motto: "Can't beat 'em, eat 'em!")

According to Landers, Parola butchered the nutria to produce a saddle of meat, soaked it in Italian dressing, and baked it for a while. Then he shredded the meat and browned it in a pan with Cajun seasonings. Landers maintains that of the ark of invasive animals he sampled during the writing of 'Eating Aliens,' nutria best approximated the taste and texture of chicken – Americans' meat flavor benchmark.