Published: May 28, 2009 06:27 pm      

A bug attack — 05/30/09

Tiny parasites are threatening ash and hemlock trees in state

After successfully escaping an invasion of the emerald ash borer in 2008, the dreaded parasitic insect has been identified in two Kentucky counties. State forestry officials are expecting the invasion to quickly spread throughout the state.

University of Kentucky extension entomologist Lee Townsend said the metallic green Asiatic beetle was found in a residential area of Jessamine County and in a woodlot in Shelby County. Although extremely small in size, the tiny insects have the potential of doing as much damage to Kentucky hardwood ash trees as another small parasite — the Southern pine beetle — did to pine trees in the state just a few years ago.

There is no shortage of ash trees for the green beetles to feast on in Kentucky. The Kentucky Division of Forestry estimates that there are 131 million while ash trees and 92 million green ash trees in the state.

Although not native to North America, the ash borers were first discovered near Detroit just seven years ago. Since then, the insects have killed tens of millions of ash trees in 11 states in the United States and two Canadian provinces. The tiny insects have no natural enemies in the western hemisphere.

A year ago, Kentucky forestry officials placed more than 3,600 traps in an effort to prevent the ash borers from crossing the Ohio River into Kentucky. Even though that effort was apparently successful, forestry officials feared that it was only a matter of time before the ash borers were in Kentucky. They were right.

And the ash borers are not the only insects threatening trees in Kentucky. Woolly adelgids — tiny aphid-like insects no bigger than an ink dot — have destroyed thousands of hemlock trees from Maine to Georgia and were first spotted in Kentucky three years ago. Since the adelgids have no natural enemies in Kentucky, state forestry officials have imported predatory beetles from the Pacific northwest to devour the tiny parasites.

Joyce Bender, head of the Kentucky Nature Preserves Commission, said hemlocks could be annihilated if the woolly adelgids are not stopped. Hemlocks are among the most popular ornamental trees in the Appalachian Mountains, and experts say losing the hemlock stands would drastically change the forest composition in the Southeast.

The greatest threat to our forests is not greedy men and women armed with chain saws, but tiny insects that look absolutely harmless but are anything but that.