Die, Weed, Die!

An alien moth munches an invasive fern into extinction

Their research has been enough to convince even skeptics that bioagents are a real alternative to spraying. "We needed to convince the state agencies that this was a long-term alternative to chemicals," Rayamajhi says. "At the beginning we didn't have the funding to disperse the insects, but now they've reallocated some of the chemical funds to insects."


In late 2000, John Volin, an infectiously energetic plant scientist at Florida Atlantic University, began looking at the steady growth of Old World climbing fern. Little was known about its biology. Not until 1978 was its spread scrutinized by two scientists, who found it growing near the shoreline in southern Martin and northern Palm Beach counties. They concluded the spore-bearing plant was a cause for worry.

Owen Richardson
The caterpillars of this moth, the Austromusotima camptonozal, eat 
Old World fern. It's the first insect released against the dreaded plant -- 
but not the last
Christine A. Bennett
The caterpillars of this moth, the Austromusotima camptonozal, eat Old World fern. It's the first insect released against the dreaded plant -- but not the last

No one became worried.

The fern, however, spent the next fifteen years diligently establishing itself in the undergrowth, then climbing upward, and finally coiling around tree branches and leaves. Starved of sunlight, the trees slowly died. The South Florida Water Management District, a state agency that's a front-line warrior against invasives, began aerial surveys of the fern in 1993 from coast to coast at 500 feet above treetops. By the end of the decade, the water district had data indicating the fern had spread to Florida's west coast and was overwhelming the tree islands of the Loxahatchee National Wildlife Refuge in south Palm Beach County.

What, Volin wondered, was the Everglades facing?

Using the data collected between 1978 and 1999, Volin devised a computer model to project the spread of the climbing fern by the year 2014. Despite knowing how rapidly the plant had multiplied, Volin was stunned by what he found. The model revealed the fern will have covered almost all the Everglades in Palm Beach, Broward, Hendry, and Collier counties. Substantial portions of Martin and Glades counties will have been covered, and the infestation will have made deep inroads into Everglades National Park in Miami-Dade County.

Volin's findings seemed too dire to be true. "I said, 'Hell, we can't share this,'" Volin recollects. So before announcing the findings in 2002, Volin and his research assistants double-checked the reliability of his prediction through painstaking marches through the Everglades. "I feel strongly that, as a physiological ecologist, when we're doing predictions -- whether it's about climate change or, in this case, an invading species -- you don't want to overstate it," Volin says. "It's like saying the sky is falling. You don't want to do some dire prediction, only to eat your words later on."

No one's calling Volin a Chicken Little.

Don Schmitz, with the Florida Department of Environmental Protection's invasive plant bureau, estimates state agencies are spending more than two million dollars a year to combat Lygodium, about eight times more than five years ago.

The Loxahatchee Refuge recently received four million dollars from Congress to fight exotics, Melvin says, and the threat of Old World fern certainly helped loosen those purse strings for tree triage. "There will be aerial spraying of islands where there aren't any native plants left and follow it up with a ground crew on the perimeter," she says.

Volin, who possesses a bantam build, impressively full goatee, and piercing eyes, is overseeing another ambitious year-long project, funded by the water district, to hunt down incipient sporelings of Old Word fern in the east-central part of the Everglades. His research team will visit each of the roughly 500 islands and, using a GPS device, record each sighting of the fern. The management district will then send out contractors who will locate the exact spot and treat the plant with a systemic herbicide that completely destroys it. It's an endeavor analogous to bicycling across the U.S. to visit every 7-Eleven: They're everywhere and you never know where the next one will spring up. Just how much this will cost won't be known until later.


On a partly cloudy morning in late May, Volin and three other researchers haul two airboats an hour south of Davie to a public dock along Tamiami Trail. This is the driest month in the Everglades. The water covering the vast expanse of grass surrounding tree islands has slowly receded during the desiccated winter months, and the routine rainstorms of the tropical season have yet to begin in earnest.

The airboats are relatively small three-seaters, each driven by a cacophonous twelve-cylinder aircraft motor. The two boats weave northeasterly for about twenty minutes, sometimes crossing patches of slough that are little but mud. They pull up to a high stand of saw grass on the east side of a tree island. The real work begins on foot. Dressed in long-sleeve shirts and long pants, they begin the fern hunt by stepping off into water that's just under two feet high.

This is the first foray into the glades for Mary Ann Furedi, a new researcher who's only recently moved from West Virginia, where she walked mountainous terrain studying ginseng. A twentysomething with longish dark blond hair, Furedi will head this new project, but she and her team will go far beyond the tasks contracted for by the water district. Among other things, they'll be trying to identify "bio-indicators," which are plants or formations that act as hospitable hosts to a particular invasive species. When such a correlation is made, a bio-indicator creates a kind of shortcut for locating invasives and determining their reproductive and growing cycles. (Melaleuca, for example, is a sucker for spots that have been disturbed by fire.)

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