In Pennsylvania, one power company is preparing to remove more than 1,500 dying ash trees, damaged by the invasion of emerald ash borers. But ash trees, rotted from the inside out by the invasive insect, aren't just found overhanging power lines. They're everywhere.

"They rot at the root system," Todd Meyers, spokesman for West Penn Power, said in a statement. "They can just keel over an entire tree."

Officials in New Jersey have set some 1,750 purple traps in trees all across the state to track the beetle's invasion. Currently isolated to southern New Jersey, it's expected the beetle will quickly make its way north, where the state's largest ash populations are concentrated. Experiments show the beetle can fly up to five miles a day.

In fact, the emerald ash borer is already chomping on trees to the north -- rotting the trees of New Hampshire and Massachusetts. The beetle has found its way into the forests of 24 states, as far south as Georgia and as far west as Colorado. It has killed millions of ash trees.

Most states have attempted to quarantine infected regions, restricting the movement of lumber from infected counties into borer-free counties. But it's hard to say whether the strategy works. Wisconsin recently located ash borers in two new counties in the north the state, dozens of miles away from the nearest infected and quarantined counties.

"It's disappointing, but not surprising, when EAB shows up in an entirely new area like this," Brian Kuhn, director of the Bureau of Plant Industry in Wisconsin's agriculture department, said in a statement. "EAB hitchhikes on firewood and other ash wood very easily, and can end up many miles from any previously known infestation. It's hard to detect at low levels, so it's generally three or four years before we find an infestation after it first begins."

There are moderately effective insecticides that can be used to save trees from an ash borer infestation. But the process of applying the chemicals -- a process both time-consuming and expensive -- makes the treatment of dense forest nearly impossible.