CONCORD, N.H. --A 2-inch-long caterpillar with a row of white dots on its back is costing New Hampshire's timber industry millions of dollars and could take a toll on next year's maple syrup industry as well.

Kyle Lombard, forest health specialist with the state's Division of Forest and Lands, said the tent caterpillar has infested about 70,000 acres. The insects eat the canopies of northern hardwoods, which doesn't kill the trees but weakens them. The caterpillars have affected mostly forests around Mount Sunapee -- and they've taken away leaves during the spring and summer.

Last year, only about 10,000 acres were affected last year in New Hampshire.

Lombard said tapping affected maples for syrup further stresses the weakened trees. He said foresters also have been forced to delay harvests in affected areas. Lombard estimates the insect has cost the timber industry as much as $5 million.

"They're in here, and they're multiplying and they're moving," Lombard said.

He said the infestation probably was carried by the wind from Vermont, where 400,000 acres were defoliated this year.

To kill its caterpillars, Vermont sprayed 1,600 sugar maples with a bacterial insecticide.

Tim Fluery, a forest resources educator with the University of New Hampshire Cooperative Extension in Merrimack, said he's not recommending spraying for maple syrup in New Hampshire just yet. It's expensive and it doesn't guarantee results, he said.

"It doesn't control the infestation outside the area," he said. "It could come back in," blown by the wind.

Fluery advises to wait for black-billed cuckoos and flies, which eat caterpillar larvae, to control the population.