Beetles to battle wetlands threat


It's like fighting fire with fire: introducing one non-native species to devour another.

The Maryland Department of Natural Resources plans to begin releasing about 60,000 European leaf beetles today on the Eastern Shore, hoping that they will eat an invasive species of plant that is smothering wetlands.

Some of the Galerucella beetles - brown bugs the size of a match head - will be freed in the area of Route 331 and the Choptank River in Caroline County, said Kerrie Kyde, an invasive plant specialist with the state agency.

The goal is to control purple loosestrife, a tall herb with vivid purple and pink flowers clustered in spikes.

The loosestrife grows in dense patches, overwhelming marshes and crowding out native Chesapeake plants such as rushes and cattails. This, in turn, drives away animals that live in marshes, such as bitterns and bog turtles.

"This is a Eurasian plant that came over in the 1800s in the ballast water of ships and started to spread," Kyde said. "It's a really pretty plant, but it tends to take over, producing millions of seeds and crowding out and shading out other things."

The beetles love to eat loosestrife. They have proven effective over the past decade in controlling the plant in New York, New Jersey, Minnesota and elsewhere. Maryland scientists released some of the beetles from 1999 to 2003, Kyde said.

Now the state is planning to release many more. Kyde said she is not worried that the beetles will multiply to such an extent that they will become a pest and compete with native insects, because they eat only loosestrife and another invasive plant species.

The beetles are choosy, and will lay their eggs only on loosestrife, Kyde said. State biologists are not concerned about the beetles becoming an out-of-control invader, she said, "because these beetles don't finish their life cycles on any other plant."

When the loosestrife is under control, the beetle populations should also drop, she said.

In Europe, where both the plant and beetle have lived for thousands of years, only small, scattered clusters of the loosestrife grow, according to a Cornell University Web site.

But in the United States, the plant has thrived without the predatory beetle, infesting wetlands in New England, the Midwest, and parts of the Northwest.

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