Vacation Season Begins High Risk Period For Spread of Emerald Ash Borer

Deadly invasive insect has been discovered in 15 states and poses a threat to many others.

Trees, Pests & People

Emerald Ash Borer attacks all species of ash trees.

Arlington, VA | May 15, 2012

As Memorial Day kicks off the vacation and camping season, another summer event takes place: adult emerald ash borers emerge from within ash trees to mate and lay eggs. These invasive tree-killing beetles can spread far and wide when their paths converge with the plans of vacationing Americans – resulting in the spread of this highly damaging insect on contaminated firewood to new locations. Sometimes described as the most destructive insect to ever invade this country, the emerald ash borer has already killed tens of millions of trees in the Midwest and Mid-Atlantic states, and is a potential threat to all ash trees nationwide.

The emerald ash borer is originally from Asia and most likely first arrived in North America in infested wood packaging crates and pallets. Because it’s a non-native species, American trees have no evolved resistance to its attacks, and it has no effective native predators. The beetle was first discovered in the United States in 2002 in southeastern Michigan. Since that time, EAB infestations have been discovered in Illinois, Indiana, Iowa, Kentucky, Maryland, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, Wisconsin, and the Canadian provinces, Ontario and Quebec.

The female beetles usually emerge in late May and early June, making early summer the most critical time for everyone to be aware of what the emerald ash borer looks like, and of the very serious threat of moving firewood. Once the emerald ash borer has infested a tree, the larvae carve shallow tunnels under the bark, disrupting the tree's ability to transport water and nutrients. These tunnels, called galleries, are what eventually kill the tree.

“Because the emerald ash borer larvae feed under the surface of the bark, a visual inspection will often not detect them,” said Leigh Greenwood, Don’t Move Firewood campaign manager, The Nature Conservancy. “When people take firewood with them on their camping and hiking vacations, they can accidentally transport these or other damaging pests, unseen in apparently clean wood. When, packing, it might seem harmless to people to load a few pieces of seasoned firewood along with their gear, but we ask that instead people buy it where they’ll burn it.”

The emerald ash borer, Asian longhorned beetle, and many other invasive insects’ spread has been aided by the movement of firewood. Firewood has been implicated in dozens of forest pest infestations found in or near campgrounds, including infestations in Massachusetts, Missouri, Ohio, Indiana, and West Virginia. 

“There are an estimated eight billion ash trees of various species in the United States, found in almost every state, all of which are vulnerable because complete eradication of the emerald ash borer is difficult,” said Faith Campbell, senior policy representative at the Conservancy. “At a policy level, we need stronger regulations in place to help prevent the entry of these types of destructive pests into the country; however, once they are here, curtailing human movement of them is one of our greatest hopes of slowing the spread.”

Many states now have quarantines on the movement of firewood, with rules varying greatly according to local jurisdictions and pest situations. In many states, regulations now limit how far firewood can legally be transported within a state, and some states prohibit the entrance of out-of-state firewood into their borders. Additionally, the USDA Animal and Plant Health Inspection Service has federal quarantines in affected states to prevent the movement of pests like the Asian longhorned beetle, emerald ash borer, sudden oak death, and other damaging pests and pathogens.

“The current federal quarantines and state regulations are only effective if people know about them, and abide by them,” said Leigh Greenwood. “It’s up to each person to take steps to help save the beautiful and critically important trees of this country’s urban and wild forests. Everyone that takes the one small step of not moving firewood could potentially save thousands of trees.”

Following are tips from the Don’t Move Firewood campaign:

• If you don’t want to keep your firewood until next winter, don’t be tempted to take bring it along on any road trips. Instead, you can give it to your next-door neighbor, burn or chip it on site, or dispose of it locally.
• Keep in mind that just because even though the wood looks clean and healthy, it could still harbor tiny insect eggs or microscopic fungal spores that could start a new and deadly infestation of forest pests.
• Obtain firewood near the location where you will burn it – that means the wood was cut in a nearby forest, in the same county, or a maximum of 50 miles from where you'll have your fire.
• Aged or seasoned wood is not considered safe to move, but commercially kiln-dried wood is a good option if you must transport firewood.
• If you have already moved firewood, and you need to dispose of it safely, burn it soon and completely. Make sure to rake the storage area carefully and also burn the debris. In the future, buy from a local source.
• Take care to respect all state and local regulations on the movement of firewood and other unprocessed wood – some areas are subject to serious fines for violations. For more information, visit
• For more information about federal quarantines in the states where the emerald ash borer has been found, please go to:
• If you notice an insect or tree disease you don’t recognize, take a photo or obtain a specimen of it, and compare it to Web site photos of the suspected pest. A good resource to help in identification is:
• If you believe you have found a new outbreak of an invasive insect or disease, contact your state department of agriculture:
• Tell your friends and others about the risks of moving firewood – no one wants to be responsible for starting a new pest infestation.

The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. The Conservancy and its more than 1 million members have protected nearly 120 million acres worldwide. Visit The Nature Conservancy on the Web at

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