AUGUSTA -- The Maine Forest Service is reminding campers heading to their favorite Maine campsites this season to leave their firewood at home.

Firewood can contain invasive insects that could seriously harm the state's forests.

"I can't begin to emphasize how important this is," said MFS entomologist Charlene Donohue. "There are several dangerous species that can destroy Maine trees, such as maples and ashes. That destruction not only could kill our forests, but also affect our important forest and tourism industries.

"All campers, especially our out-of-state visitors, can do a lot to preserve our woods heritage and our economy by following this simple suggestion."

Campers should buy firewood at their camping destination.

Campers at state parks, particularly those from other states, will be asked about their firewood, according to Tom Morrison of the Maine Bureau of Parks and Lands. Signs warning of the problem also will be posted at the parks this summer, he said.

One highly dangerous insect, the Asian longhorned beetle, already is too close to Maine. This beetle, which kills maples, birches, poplars, willows and other tree species, already has been found in Worcester, Mass., as well as in New York, New Jersey and Canada.

A federal quarantine is in place, prohibiting the transportation of firewood across quarantine lines.

"If this nasty bug ever gets established in Maine, it could destroy our maple sugar industry and our foliage tourism industry," Donohue said. "This is serious business."

Invasive species can lodge in, on or under firewood bark, or be deep within the wood.

The insects often can't be seen in the wood. Infected wood that is transported to "clean" locales, especially if it's left lying around for any length of time, can allow the spread of the bad bugs, Donohue said.

Left alone, an invasive insect might spread only a few miles in one year, Donohue said. Carried in firewood, it can spread hundreds of miles in one year.

One of the most serious invasive bugs is the emerald ash borer, which has the potential to kill all ash trees in North America. Ash wood, in particular, is used to make baseball bats.

The emerald ash borer, which can kill a tree in three to five years, has killed millions of trees in the Midwest and has been found, as of 2008, in Michigan, Illinois, Indiana, Ohio, Pennsylvania, West Virginia, Virginia, Wisconsin, Missouri, Maryland and Ontario.

Just last week, state officials in Minnesota reported the presence of the emerald ash borer in that state. Three infested trees were found in a line of trees in front of some town houses in a St. Paul neighborhood.

Donohue has been giving firewood and invasive species training to Maine Bureau of Parks and Lands staff, Morrison said. Park staffers will be on the look-out regarding firewood, particularly that brought in by campers from areas where known insect problems exist, the BPL operations director said.

"We will be talking to campers, particularly campers from where there is a known problem," Morrison said. "If they bring in firewood, we will be asking them to burn it the first day."

Firewood will be available at most parks, Morrison said. Campers can buy it there or from local vendors, he said.

Donohue asks everyone to remember these four safety tips:

* Use firewood you obtain locally.

* Don't transport firewood more then 50 miles.

* Don't take firewood home that you got elsewhere.

* If you've already transported firewood, don't leave it or bring it home. Burn it.

For more information, visit www.maine.gov/firewood.