Gypsy moths on the rebound

March 09, 1998|By LISA GRAYBEAL

Gypsy moths on the rebound

Gypsy moth populations are on the rise in Washington County and officials at the Maryland Department of Agriculture are planning to spray nearly 700 acres of trees this spring before the insects take hold.

An insecticide made partly from bacteria that occurs naturally in soils will be sprayed aerially around the second and third weeks of May on 673 acres at Chestnut Grove Park in the southern part of the county, and in the Mount Aetna area in the northern part, said Betsie Handley, regional entomologist with the Forest Pest Management section of the state Department of Agriculture.

"We noticed the gypsy moth population had returned to levels that could be damaging to trees if they aren't sprayed," Handley said.


State Department of Agriculture officials conduct annual gypsy moth egg mass surveys in 20 counties and in Baltimore City as part of a federal, state and county cost-share Cooperative Gypsy Moth Suppression Program.

When surveys indicate the presence of gypsy moth larvae, aerial application of insecticides may be used to prevent damage and death to forest and shade trees. Trees defoliated for three consecutive years usually die, according to officials.

Gypsy moths hatch in late April or early May and begin eating young leaves, with a preference for oak, sugar, maple, beech and aspen trees.

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, Handley said.

"What we're trying to do is prevent a big problem," said Sandy Scott, horticulture consultant at the University of Maryland Cooperative Extension Service in Hagerstown.

The extension office, at 1260 Maryland Ave., is hosting an open house on Tuesday, March 10 from 6 to 8 p.m. in which state Department of Agriculture officials will present an informational meeting about the gypsy moth spraying schedule in the county.

In Maryland, the gypsy moth caterpillars chewed through about 200,000 acres of forests in the early 1990s. In 1997, the number of acres of defoliated trees was down to 576 acres, the lowest total since 1980, according to figures provided by the state Department of Agriculture.

In 1997, agriculture officials sprayed 9,009 acres of private, county and municipal land in seven counties, plus 1,728 acres of state land in four counties. About 88 percent of the treated acres were on the Eastern Shore.

The state spent an average of $1.5 million a year spraying for gypsy moths during the peak years.

For the past several years, gypsy moth outbreaks have been in a downward cycle in Washington County, Handley said.

A fungus that's lethal to the insects is one of the things that has kept the populations down, she said.

The gypsy moth caterpillar picks up the fungal spores as they crawl up and down the trees, creating spores in their systems, Handley said.

The wet, cool springs in 1995 and 1996 enhanced the survival of the fungi. But last year's warm and dry spring was a poor environment for fungi growth and the gypsy moth population rebounded, she said.

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