Tamarisk fight looking hopeful

Beetles that destroy water-sucking tree appear to take hold

Ellen Miller, Special to the News

Published July 28, 2006 at midnight

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GRAND JUNCTION - A year after beetles developed by scientists were released in selected tamarisk infestations at three sites in Colorado, the project is showing encouraging signs that the bugs will significantly defoliate the water-sucking trees that clog most Western rivers.

"It's still wait and see, but so far it's very encouraging," Dan Bean, manager of the Palisade Insectary, which helped develop the tamarisk leaf beetle, said Thursday. "If everything goes well, we'll see significant effects in two years."

Bean said 8,000 tamarisk leaf beetles, released last August in Horsethief Canyon west of Grand Junction, along the South Platte River in Adams County open space and at Bonney Reservoir in Yuma County, are taking hold and not being eradicated by ants, their main predators.

Releases in 2001 at four sites, two in Nevada and two in Utah, have matured and beetles are defoliating hundreds of acres of tamarisk. Bean also said that beetles released in 2004 near Moab, Utah, are taking hold.

The tamarisk, a tree native to Eurasia, has crowded out native species such as willows and cottonwoods and sucked up vast amounts of water in the West.

Labor-intensive efforts to eradicate tamarisk cost $1,500 to $3,000 per acre. The tamarisk leaf beetles may be able to do the job for less than $10 per acre, according to U.S. Bureau of Land Management spokeswoman Mel Lloyd.

The beetle, officially Diorhabda elongate deserticola Chen, has undergone more prerelease testing than any other biological control agent in the country's history, Lloyd said.

The BLM and the Palisade Insectary, operated by the Colorado Department of Agriculture, both play a role in the release and monitoring of the insect.

"They're slow and steady, but doing well,'' Bean said.

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