BANGOR (AP) – A voracious insect that threatens hemlock trees has established itself in York County, infesting an estimated 600 acres, according to the Maine Forest Service.

The hemlock woolly adelgid started killing trees in southern New England decades ago and foresters have said it was probably only a matter of time before it showed up in Maine.

The state has been under quarantine since 2000, banning the importation of nursery hemlocks for fear they could spread the bug. A few infested ornamental trees have been destroyed, mostly along the coast.

The natural pattern of the York County infestation indicates that the tiny, flightless insects probably blew into Maine on a windstorm or hitched a ride with a bird, state entomologist Dave Struble said.

“I think they’ve probably been trickling in for some time,” Struble said. “The good news is that the population is extremely low right now.”

The adelgids feed on the sap of hemlock trees; a fully infested tree can die within five years.

The adelgid most likely was brought to the United States from its native Asia on a tree. Once in North America, the insect had no natural predators and was able to develop alarming populations.

Forest cover has disappeared in some parts of southern New England, where the infestation has grown out of control.

“Whole parks are dead,” Struble said.

In Maine which relies on hemlock for 10 percent of its pulpwood, an infestation would be disastrous.

“To potentially lose 10 percent of your softwood is a big concern, no matter what,” Struble said. “Losing this is not acceptable.”

State scientists are surveying York County forests this winter in an attempt to determine how pervasive the bug has become.

But it is difficult to even verify the presence of the microscopic bug during winter when the white, cottonlike egg sacs it lays on the underside of hemlock branches in the spring and fall are hard to spot.

January’s arctic weather could prove beneficial, as hemlock woolly adelgids can’t survive bitter cold.

“You can get complete kill at 25 below,” Struble said. “But just how much do you want to bank on good luck and weather?”

The state is pursuing substantial federal grant money to attack the infestation once the snow melts in the spring.

The state has been experimenting with predatory Asian beetles that have shown promise against adelgids in the lab. Beetles most likely will be released next spring.

Pesticide applications also have been effective in some places.

Regardless of which weapons the state ultimately chooses, the battle against the hemlock woolly adelgid will be a long and frustrating one, Struble said.

“It’s like wrestling Jell-O,” he said.

AP-ES-02-09-04 1043EST