Nearly dormant here for several years, gypsy moth starting to make comeback

Caterpillars defoliate 46,183 acres this year

September 19, 2001|By Joel McCord | Joel McCord,SUN STAFF

Gypsy moth caterpillars chewed their way through twice as many acres of oak, maple and hickory trees this spring than in the spring of last year, and officials at the state Department of Agriculture expect the increase to continue next year.

Gypsy moth infestations tend to be cyclical, and the cycle appears to be on the upswing, said Mark Taylor, coordinator of the Department of Agriculture's forest pest management program.

In the early 1990s, the caterpillars devastated thousands of acres of oaks throughout the state. Infestations slowed in the middle of the decade, then began gaining strength again in the last three years.

This year, the moths defoliated 46,183 acres in 15 Maryland counties, compared with 23,231 acres last year. The figures - highest in five years - are less than half the record 133,062 acres defoliated in 1990.

The acreage wasn't "a surprise to me, and it won't surprise me if what needs to be sprayed in 2002 is double or triple what we did this year," Taylor said.

It is unclear, however, whether that means agriculture officials will ask for more money for spraying.

The agriculture department, which spends $300,000 to $500,000 a year to spray insecticides on forests from Worcester County on the lower Eastern Shore to the Garrett County in the mountains, hasn't finished the surveys used to predict how much forest will need to be sprayed.

"How much is still being discussed," Assistant Secretary Charles Puffinberger said yesterday. "We've budgeted for 26,000 acres in 2002, but if we need more than that, we'll have to go to the legislature."

Scientists try to predict the extent of the gypsy moth outbreak by counting egg masses on trees in the fall.

One attack of gypsy moth caterpillars may not kill a tree, but repeated attacks could, depending on the size, genetic make-up and health of the tree.

Gypsy moths do little more than eat and reproduce. The caterpillars hatch in the spring and feed on tree leaves until they are ready to spin their cocoons, usually in late June. The moths that emerge live long enough to mate, reproduce and die.

The damage the caterpillars cause to trees is so devastating because they begin feeding after the trees have depleted their leaf-making energy. Without leaves there is no photosynthesis, which nourishes the tree.

The worst loss in the state this year was in Allegany County, where 25,194 acres of hardwoods were stripped bare - three times the acreage of 2000 and more than all the other counties combined.

Although the damage increased sharply in some counties, it dropped considerably in others. In Frederick County, the moths stripped the leaves off 2,402 acres of trees in 2000, but only 799 acres this year.

Agriculture officials credited spraying for the decreases, and department Secretary Hagner R. Mister promised "to respond aggressively to the outbreaks to protect Maryland's valuable urban and rural forest land."

But environmentalists are leery of spraying, fearing it may do more harm than good.

"We've always questioned the validity of [using chemicals] vs. what it is you're trying to protect," said Theresa Pierno, Maryland executive director of the Chesapeake Bay Foundation. "There have been a lot of studies that have found that many times spraying programs allow the moths to maintain at a lower level and they still continue to cause damage to the tree."

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