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They Came, They Stayed, They Conquered

Invasive species are wreaking ecological havoc in our region.

Pastor Beverly Clayburn is framed bya loop of kudzu, which is taking over Straight Gate Church in Grays Ferry.
Pastor Beverly Clayburn is framed bya loop of kudzu, which is taking over Straight Gate Church in Grays Ferry.Read morePETER TOBIA / Inquirer Staff Photographer

For several years, foresters and entomologists have watched with horror - and dread - as a half-inch green bug spread outward from Detroit, leaving 25 million dead ash trees behind. Survey crews from Michigan to Pennsylvania stalked the forests; if it showed up, they wanted to know.

Three weeks ago in western Pennsylvania, two surveyors pulled to the side of the road and got out of their car. "Stand still," said one, noticing an iridescent insect on the other's back.

The emerald ash borer had landed.

Now, with reports of suspicious ash tree damage from surrounding counties, state and federal officials are planning still more surveys - and trying to figure out what on earth to do next.

Not so long ago, botanists, aquatic scientists and others were optimistic about their ability to wage war against the arrivistes. And time and again, the newcomers - not just ash borers, but zebra mussels, snakeheads, even stiltgrass - thwarted them.

"It's become the weary acceptance that once they're here, they're here to stay," says Dan Tredinnick, spokesman for the Pennsylvania Fish and Boat Commission.

"It's more trying to do what we can to slow the spread."

Half of all plants and animals now on endangered species lists owe at least part of their decline to the rise of invasives.

Invasive plants rank second only to habitat destruction by humans in their ability to wipe out native species. Aquatic invasives, which are able to hitch rides downstream, are deemed even more damaging in some ways than chemical pollution. (At least pollutants don't self-propagate.)

On May 17, two fisheries biologists working in Tioga County discovered the first zebra mussels in Pennsylvania's stretch of the mighty Susquehanna River.

Two weeks later, the potentially invasive Chinese mitten crab, found in the Chesapeake in 2005, was caught in Delaware Bay - and then the Hudson River.

June 22 marked the emerald ash borer's Pennsylvania debut, on the side of the road in Cranberry Township, about 20 miles north of Pittsburgh.

In the five years since the beetle's appearance in the United States, all attempts to eradicate the Asian import have merely slowed its journey north, west, south and, finally, east.

In all likelihood, "it's going to be here sooner than we expect, unfortunately," says Bill Graham, an arborist with Care of Trees in King of Prussia.

That, and who knows what else.

"There's always something new coming at us," says Coanne O'Hern, the U.S. Department of Agriculture's Pennsylvania plant health director.

Lest we forget the old: Legions of "invasives" seem familiar to most, from gypsy moths to West Nile virus to multiflora rose, which is "now in every county, every municipality, and I would go so far as to say it's on every property tax parcel in the entire state," says Melissa Bravo, a Pennsylvania Agriculture Department weed scientist.

Several years ago, a Cornell professor estimated invasive species cost the United States $100 billion a year.

"You can quibble around the edges," says Chris Dionigi, assistant director of the National Invasive Species Council, but that figure "is probably the right order of magnitude." The federal government alone spends more than $1 billion.

New Jersey has been spared so far - its ash-borer future to some extent depends on Pennsylvania - but the Garden State has its own battle with the Asian long-horned beetle, which also kills trees. (While chewing through North Jersey, the longhorn to date has eschewed Pennsylvania.)

At the Schuylkill Environmental Education Center, along Philadelphia's wild northwestern border, executive director Dennis Burton has been in pitched battle with Japanese stiltgrass, bittersweet and windberry, managing only a kind of detente after six years.

"This is the new optimism," Burton says. "It's possible we'll be able to have natives living side by side with nonnatives."

To Dionigi, slowing the nonnatives' spread at least buys scientists time to develop new control methods. "That which may seem completely impossible today might be a very different story 30, 40 years from now."

Bravo, the weed scientist, has pretty much bowed to defeat when it comes to multiflora rose, not to mention mile-a-minute vine and a few others.

But she's declared war on kudzu.

Known as the weed that ate the South, it's now vining well above the Mason-Dixon Line.

At the Straight Gate Church, in the Grays Ferry section of the city, no matter what they do - douse it with poison, chop it to the ground - the kudzu keeps coming back.

"It rains, and it'll grow two or three more feet," says Pastor Beverly Clayburn.

Despite its vigor, kudzu is still in only 81 isolated spots in Pennsylvania - as far as officials know. But with temperatures rising - global warming is predicted to affect the range of many species, indigenous and otherwise - the kudzu is producing viable seeds. The plants are spreading.

With $50,000 from Harrisburg, Bravo is attacking 26 sites in 12 counties on two fronts: Cut the plants to the ground and spray herbicide on the remaining nubs to kill the roots.

She estimates the surge will take three years and cost $2,000 per site. Her team goes back to each spot weekly to monitor.

And to cut.

Meanwhile, for an exercise in futility, consider the northern snakehead. When the bizarre, toothy fish was first found in a Maryland pond in 2002, officials drained the pond and poisoned the mud.

"They thought they had it contained," recalls Tredinnick, of the Pennsylvania fish commission. "Guess what. Now they have snakehead fishing contests on the Potomac."

Snakeheads showed up a few years ago at South Philadelphia's FDR Park. At the time, there was confusion about which lake they were in.

"Now it's easier," deadpans Academy of Natural Sciences ichthyologist Richard Horwitz. "They're in both."

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