LEES FERRY, Ariz. — In this corner of America known for its vast landscapes, rugged mountains and deep river canyons, signs of the havoc created by the minuscule tamarisk beetle are everywhere.

For miles along the banks of the Colorado River, hundreds of once hardy tamarisk trees — also known as salt cedars — are gray and withered. Their parched branches look like victims of fire or drought.

But this is not the story of beloved trees being ravaged by an invasive pest — quite the opposite. Farmers, ranchers and the water authorities here are eager to get rid of the tamarisk trees, which are not native to Arizona and which they say suck too much water.

They have welcomed the beetles, which have made their way from Colorado and Utah over the last decade, and have watched with delight as the centimeter-long workhorses have damaged the trees by eating their spindly leaves. The hope is that the beetles will now rid Arizona of the trees.