A small but highly destructive metallic-green beetle — the emerald ash borer — has caused the death of approximately 25 million ash trees in less than a decade.

The emerald ash borer is not a pest in its native Asia. But in North America, where ash trees have not had tens of thousands of years to evolve resistance to the beetle, it is destroying native ash trees at an alarming rate — and has the potential to cause billions of dollars of damage.

Nature.org spoke with Frank Lowenstein, deputy lead for The Nature Conservancy’s Global Invasives Species Team, about the emerald ash borer, how we're working to stop it—and how you can help.

Nature.org: How and when did the emerald ash borer get to North America — and how far has it spread?

Frank Lowenstein: The emerald ash borer is a foreign import, like chestnut blight and the Asian longhorned beetle — two other invasive species that have attacked North American trees.

Evidence suggests that it arrived as a stow-away in wood crates and packing material from Asia in the early 1990s. It was first discovered in Michigan in 2002, and has since spread from Maryland to Missouri, affecting eight states and the Canadian province of Ontario. It’s quite a traveler for a quarter-inch-long beetle.
 

Nature.org: Is it spreading on its own?

Frank Lowenstein: No — people’s actions are making the problem worse.

On its own, the emerald ash borer can travel only short distances. But the beetle can quickly spread hundreds of miles when businesses and average citizens unknowingly move it in firewood, logs and nursery trees.

There’s also a risk that it could move in wooden crates or pallets.

Many infestations have turned up near campgrounds, so people moving firewood is thought to be particularly troublesome.
 

Nature.org: How do I tell if ash trees in my neighborhood or forest are at risk?

Frank Lowenstein: All 16 species of ash tree in North America — 8 billion trees total — are at risk. And these trees are found in forests, cities and suburbs.

In the near future, trees in the Northeast, Mid-Atlantic, the Midwest and the Great Plains are at greatest risk.
 

Nature.org: What is the potential impact — both economic and ecological — of the emerald ash borer?

Frank Lowenstein: The ecological and economic costs to the United States could be staggering. From an ecological standpoint, ash trees:

• Produce oxygen and store carbon dioxide;
• Protect cold water habitats for species like native trout by creating shade and preventing erosion
• Are a major part of critical wetland habitats throughout North America; and
• Conserve energy and improve quality of life by shading sidewalks and streets in thousands of cities and suburbs.

Many wood products — such as flooring, furniture, tool handles and baseball bats — are made from ash trees, and losses to this industry could be $25 billion in the eastern states alone.

The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) has estimated that the total value of urban ash trees in the United States is between $20 and $60 billion.

It’s going to require a tough, relentless and expensive fight to control this pest. And if the fight is not successful, the consequences for ash trees throughout North America are dire.
 

Nature.org: What is The Nature Conservancy doing to combat the spread of the emerald ash borer and other pests?

Frank Lowenstein: We’re working in coalition with many partners to:

• Raise awareness about the dangers of moving firewood;
• Stop the spread of this insect; and
• Prevent the invasion of other bugs before they arrive.

Much of this involves public education, and the Conservancy has developed an innovative new program with our partners to educate the general public specifically about reducing the movement of firewood.

We are also working with APHIS on eradication programs and with researchers from across the nation and New Zealand to understand the economic impacts of this insect.
 

Nature.org: What can readers do to help?

Frank Lowenstein: First and foremost: Don’t move firewood! Gather or buy firewood where you plan to burn it.

You can also keep an eye out for infestations in your community. Here are the tell-tale signs that an ash tree is probably infested with the emerald ash borer:

• A “D-shaped” hole in the bark, measuring an eighth of an inch wide, where the adult beetle has exited the tree.
• Unusually high woodpecker activity in your area, as they are known to feast on emerald ash borer larvae.

Nature.org: What should readers do if they spot an infestation?

Frank Lowenstein: You should contact APHIS, which is responsible for responding to new invasions.

Nature.org: How can we prevent this kind of invasion from happening again?

Frank Lowenstein: Improved regulations can prevent new invasions. For the first time in over 85 years, the USDA is revising its regulations that aim to prevent new invasive pests and pathogens from arriving on live plants.

The Nature Conservancy is working hard to ensure that USDA’s revisions are effective, and we’re urging fast action so we don’t face more invaders like the emerald ash borer.

Nature picture credits (top to bottom, left to right): Photo © David Cappaert (adult emerald ash borer); Photo © Frank Lowenstein (Frank Lowenstein).