Gypsy moth comeback leaves landowners aghast

June 18, 2000|By ANDREA ROWLAND

LOCUST GROVE - There's a battle on South Mountain, but it isn't between Civil War armies.

Rich Haden pulled a knife from his pocket and pierced one of the thousands of fuzzy caterpillars carpeting tree trunks along a more than two-mile stretch near the Appalachian Trail on South Mountain between Reno Monument and Locust Grove roads.

Green "leaf juice" seeped from the wound.

Haden and his friend Eric Garns thought the leaf-munching gypsy moth caterpillars were no longer a problem in Washington County, they said.

The co-owners of Hagerstown Contractors Inc. bought 30 wooded acres just south of the infested area off Locust Grove Road to build their own homes.


The state has awarded more than $8 million for land preservation efforts in the area to protect the site of a Civil War battle, but Haden and Garns fear the gypsy moth infestation will render their oak-filled land worthless, they said.

"We don't get too excited about a lot of stuff, but we're really excited about this," said Garns, 35. "It's enough to make us cry."

The gypsy moth is the most destructive pest of forest and shade trees in Maryland, said Bob Tichenor, chief of the Forest Pest Management Section of the state Department of Agriculture (MDA).

"And they're coming back," Tichenor said.

Gypsy moth caterpillars chewed through about 200,000 acres of Maryland forests in the early 1990s. In 1997, the number of acres of defoliated trees was down to 576, according to MDA figures.

Forest pest management officials next week will conduct aerial surveys to determine the amount of damage so far this year, but it's already obvious that there's been a sharp rise in the caterpillar population, Tichenor said.

"It's apparent the gypsy moths had an unusually high survival rate this year," he said. "This may be a one out of 20- or 30-year event."

Diseases, predators and parasites reduce gypsy moth populations, but insecticides must be used to protect and preserve trees when these natural mortality agents don't work well enough, Tichenor said.

That's seems to be what has happened this year, he added.

Drought conditions have contributed to the explosion of gypsy moth populations in Washington County, said Tom Lupp, assistant regional entomologist with the Forest Pest Management Section.

Numbers of the pests, which are killed in part by a fungus that thrives in wet conditions, have multiplied over the past three dry years, Lupp said.

Haden and Garns walked across a forest floor littered with chewed-through leaves. Gypsy moth excrement sounded like rain as it fell from the treetops. Clusters of the insects crowded tree trunks and the undersides of leaves.

Garns pointed towards acres of skeleton-like trees.

"It looks like the middle of December," he said. "It breaks your heart when you see it- how devastating these pests are. I can't believe how such a little bug can do so much damage."

Gypsy moths hatch in mid-to-late April or early May and begin eating young leaves, with a preference for oak and aspen trees, and a taste also for a list of hardwoods that includes birch, sugar maple and beech trees, Lupp said.

Trees defoliated for three consecutive years usually die, according to officials.Maryland's Cooperative Gypsy Moth Suppression Program spent an average of $1.5 million a year fighting the gypsy moth problem during the peak years. That figure has decreased with declining insect populations, Tichenor said.

Wet, cool springs in 1995 and 1996 enhanced the survival of the Japanese fungi that is lethal to gypsy moths. For the first time in 15 years, insecticide wasn't needed in 1997, Tichenor said.

But drought conditions during the last three years created a poor environment for fungi growth, and the gypsy moth population rebounded, Lupp said.

Gypsy moths defoliated 1,197 acres statewide in 1999, Tichenor said.

The Forest Pest Management Section conducts an integrated pest management program for the insect- which includes monitoring, assessment, education and pest control actions- to minimize unnecessary losses, he said.

"We definitely try to keep ahead of it as best we can."

MDA officials conduct annual gypsy moth egg mass surveys each year to determine the extent of the problem, Lupp said. When surveys indicate the presence of gypsy moth larvae, aerial application of insecticides may be used.

It's best to spray the voracious insects when they're in the second larval stage of growth and the leaves on the trees are about 50 percent developed, Lupp said.When the gypsy moth suppression program started in 1987, about 23,500 acres in the county were sprayed, according to MDA data.

More than 5,800 acres were sprayed this year in Washington County, up from the 2,390 acres sprayed in 1999, Tichenor said.

Nearly 8,000 county acres were sprayed in 1994. That number dropped to about 1,700 acres in 1995 and 1996, and about 700 acres in 1998.

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