County and state agriculture officials are monitoring Howard for the "green menace" -- a beetle capable of devastating the area's ash tree population.

The beetle, the emerald ash borer, is a non-native insect whose larvae feed beneath the bark of ash trees, eventually killing the tree.

The beetle has yet to be discovered in Howard County, although Steve Parker, the county's superintendent of highways, said it's only a matter of time. Efforts to contain and eradicate the beetle already are underway in nearby Prince George's and Charles counties, where thousands of trees have been cut down.

"It will come into Howard County. It's not a matter of if, it's when," said Parker, a licensed tree expert and certified arborist who serves as chairman of the county's Forestry Board. "It's going to be devastating once it gets here."

Native to Asia, the emerald ash borer was first found in the United States, in Michigan, in 2002. It has since been found in a dozen other states, including Maryland, where it was first identified in Prince George's County in 2003 and again in 2006. It was discovered in Charles County in 2008.

The beetle is responsible for the death of more than 25 million ash trees in the Midwest, according to the U.S. Forest Service.

About 42,000 ash trees have been cut down in Maryland since 2003. Some 6,000 of those trees were removed earlier this year from 3,600 acres of infested land in Waldorf, in Charles County, and Clinton, in southern Prince George's County, according to the state Department of Agriculture.

Maryland officials also have instituted a ban on transporting firewood, lumber and nursery stock out of certain areas.

Over the past year, the state Department of Agriculture has installed 201 monitoring devices, which function as beetle traps, in ash trees around Howard County, according to Julie Oberg, a spokeswoman for the state Department of Agriculture. The traps are purple boxes placed about 20 feet up in the tree. The traps -- 2,478 statewide -- are checked every two weeks.

Additional efforts to stop the beetle from spreading include a new chemical treatment for ash trees and the release of parasitic wasps that attack the beetle's eggs and larvae, Oberg said.

A common tree

Ash trees are the most common street tree in Baltimore and also make up about 20 percent of the Baltimore area's streamside trees, which are important to the Chesapeake ecosystem, according to the state Department of Agriculture and Department of Natural Resources.

Parker likened the potential effect of the emerald ash borer to that of Dutch elm disease, which wiped out most of the Baltimore region's American elm trees in the 1960s and 1970s.

In response to a growing concern over the emerald ash borer, the county took ash trees off its planting list about two years ago, Parker said.

The ash once was one of the most popular landscaping trees planted by the county, as they do well in the climate, are fast-growing and display vibrant fall color, Parker said.

He did not know how many ash trees Howard County has, but he estimated that the county has planted between 4,000 and 6,000 of the trees since 1970, including many in the older areas of Columbia.

Parker said he has received calls from some residents who fear ash trees near their homes suffered symptoms of the beetle. But so far, he said, investigations of those trees have found them simply in natural decline.

About the emerald ash borer

* Agrilus planipennis is naturally found in eastern Russia, northern China, Japan and Korea

* first found in the United States, in Michigan, in 2002, and likely transported in packing materials

* adult beetles are bright, metallic green and about 1/2 inch long and 1/8 inch wide with a flat back

* larvae are creamy white and leg-less, with flattened, bell-shaped body segments

* May to August: adults lay eggs on ash tree bark, eggs hatch into larvae and tunnel into tree

* August to October: larvae feed under bark, creating "S"-shaped patterns

* May to June: adults emerge leaving "D" shaped exit holes

Symptoms of infestation

* foliage dying from the canopy of the tree

* sprouts growing from the tree trunk and roots

* distinct exit hole, shaped like the letter "D" with one flat side and one curved side

* bark splitting vertically

* larvae feed beneath bark in a pattern that weaves back and forth

* an increased number of woodpeckers are drawn to the tree to feed on larvae

Source: emeraldashborer.info

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