2011-06-09 / Family

Emerald Ash Borer Is A Growing Threat

By Beth Brelje

STROUDSBURG, Pa. (AP) – An invasive beetle species has prompted the state to release foreign parasites – miniature wasps – into three Pennsylvania forests this week.

The emerald ash borer, with its insatiable appetite for all species of ash trees, threatens to wipe out all ash trees in the United States, said Donald Eggen, forest health manager for the division of forest pest management for the Pennsylvania Department of Conservation and Natural Resources.

Ash is the favored wood for baseball bat maker Louisville Slugger, and black ash is prized in some Native American traditions for its use in basket weaving.

The threat to ash trees is so serious that the movement of certain wood is quarantined across Pennsylvania.

The U.S. Department of Agriculture has placed purple traps in trees across the state, including some along I-84 outside of Milford in Pike County.

Luring beetles with the scent of stressed ash trees, the traps are used as a detection device.

If just one beetle is captured, the area is considered infested, Eggen said. None have been found in Pike or Monroe counties yet.

The emerald ash borer hitched a ride from Asia, where the trees are resistant to the bug and it has natural parasites.

It was first discovered in the United States in Michigan. Without parasites to keep the population in check, the ash borer has eaten its way past the Pennsylvania border and continues to advance east.

Females lay eggs on the bark of ash trees. Larva bore through the bark and start eating, leaving “S’’-shaped trails.

The larva bore through so much of the trunk that the tree can’t draw nutrients, and it dies, Eggen said.

Several thousand parasitoids, tiny wasps, were being released this week in three parks: North Park and Deer Park in Allegheny County and at State Game Lands 252 in Union County.

The wasps will attach to emerald ash borers, ultimately killing them. It is the first time a parasitoid has been released in Pennsylvania.

Still, the outlook for ash trees is grim.

“The emerald ash borer is here to stay. I can’t eradicate it,’’ Eggen said. “This is just one invasive species we are dealing with.’’

Sven-Erik Spichiger, an entomologist for the Pennsylvania Department of Agriculture, agrees.

“The emerald ash borer is not going to stop for anything. We are in damage control mode now; we are not in control mode,’’ Spichiger said.

He warns of another threat: the Asian longhorned beetle, which is similarly attacking maple trees, including syrup-producing sugar maple.

These beetles have not been seen in Pennsylvania, but sizable populations were detected in Worcester, Mass., and Carteret, N.J.

“The Poconos are considered a high-risk area for the Asian longhorned beetle because of all the visitors from infested places,’’ Spichiger said.

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