(8/1) Rectangular purple boxes attached to trees are showing up all over and some folks are wondering why.

Not too long ago, many Frederick County landowners were worried about the damage that gypsy moths would do to trees. Now the concern is the emerald ash borer.

As the name suggests, the emerald ash borer bores into ash trees, which eventually kills the tree. The purple boxes are traps.

The Maryland Department of Agriculture has placed the ash borer traps throughout Western Maryland, including Frederick County to try and stop the spread of the borer throughout the state.

"The purple rectangular boxes you see on trees throughout the county are not wrecked box kites; they are traps to monitor whether or not emerald ash borer is in the vicinity. These traps have the odor of weakened ash to attract the bugs," reported the Frederick County Forestry Board in its July meeting minutes.

Maryland's problem with the emerald ash borer began in 2003 when a nursery inspector found infected trees in a Prince George's County nursery. The trees had been illegally shipped from a quarantined area in Michigan. While the Maryland Department of Agriculture was able to seize and destroy most of the trees, 25 had been sold. As a precaution the MDA acted as if all trees within a half mile of the known-infected trees had also been infected.

The action was too late; the emerald ash borer had spread to trees that hadn't come from the Michigan nursery. As of April this year, around 42,000 ash trees had been removed and destroyed from 17,000 acres in Maryland.

In Frederick County, the Planning Division of the Division of Permitting and Development Review issued an indefinite ban on the use of ash trees in September 2006. A memo by Stephen O'Phillips, Principle Planner, prohibited ash trees for use in forest plans or street-tree planting plans and landscape plans as part of site plans, improvement plans or preliminary plats.

The memo also prohibited the planting of ash trees on "approved, signed forest plans, street-tree planting plans or landscape plans if a list of substitution species is also listed on the approved, signed plans. In those cases, applicants will be directed to use the substitution species in-lieu of Ash Trees."

The emerald ash borer has killed tens of millions of trees in southeastern Michigan where the insect was first discovered in 2002. The states of Illinois, Indiana, Kentucky, Minnesota, Missouri, New York, Ohio, Ontario, Pennsylvania, Quebec, Virginia, West Virginia and Wisconsin are all experiencing similar losses.

The insect is native to Asia and is believed to have come to the United States in solid wood packing material from Asia in 2002. It was first found in the Detroit area in July 2002. According to Maryland Department of Agriculture officials, the borer problem is more serious than the gypsy moth problem and as bad as the chestnut blight that decimated the American chestnut tree population.