Scientists from Cornell University will help the Montezuma National Wildlife Refuge in Seneca Falls, N.Y., exact revenge against purple loosestrife, a beautiful but prolific weed that chokes wetlands. More than 20,000 Galerucella pusilla and G. calmariensis -- loosestrife-specific, leaf-feeding beetles without a common name -- will be released Thursday, July 17, at 9 a.m. at the refuge.

Last year, the scientists, in cooperation with the U.S. Fish and Wildlife Service, released a few hundred beetles as a test to combat the purple loosestrife at the refuge. The release of these biological control beetles has been approved by the U. S. Department of Agriculture. Essentially, the beetles eat the leaves of the purple loosestrife, thus killing it.

"They are my little insect friends," said Bernd Blossey, director of the Biological Control of Non-Indigenous Plant Species Program at Cornell's College of Agriculture and Life Sciences. Because loosestrife's natural predators were in such short supply, Blossey has been rearing the leaf-feeding beetles to distribute nationally since 1993. Last year, the program shipped 360,000 beetles and this year they expect to ship about a half-million.

Several years ago there were as many as 1,500 acres of purple loosestrife at Montezuma. The U.S. Fish and Wildlife service flooded the refuge deeper than normal in many wetland areas, trying to reduce the loosestrife population through stress, but it also negatively affected the other plants. Biological control through its natural predator -- the beetles -- is preferred. This year, there are about 400 acres of purple loosestrife left at the refuge.

Purple loosestrife, Lythrum salicaria L., is an exotic plant from Europe that was introduced into North American wetlands early in the 19th century -- likely coming over in the ballast of trading ships, Blossey said. It also was used as medicinal herb in the treatment of diarrhea, dysentery, bleeding, wounds, ulcers and sores. The plant proliferated and put a stranglehold on many wetland areas across the continent -- degrading food, shelter and nesting sites for wildlife.

Well-established along the New England seaboard and carried along inland waterway routes such as the Erie Canal, the invasion of purple loosestrife did not abate. Today, throughout North America every contiguous American state, except Florida, and every Canadian border province, suffers from the loosestrife invasion.

The mass production of these beetles was funded through a wildlife restoration grant from the U. S. Fish and Wildlife Service, Division of Federal Aid, and the North American Wetlands Conservation Act (NAWCA).

With biological control, Blossey explained, the loosestrife is kept at manageable levels. A few of the plants survive, but they don't put a choke-hold on the natural habitats. "Purple loosestrife is too abundant now, but in about ten years the numbers will be reduced and we'll be able to really enjoy it," he said. "The insects will keep it in check."