BATH

Already plagued with the dastardly winter moth and browntail moth, the city of Bath is preparing for the next voracious insect — the emerald ash borer.

An invasive species from Asia, the emerald ash borer has destroyed hundreds of millions of ash trees in 34 states in the past 15-plus years. The insect lays eggs in the tree’s bark, where they hatch and then bore into the tree to feed, before eventually emerging as adults and starting the process anew.

The emerald ash borer was first discovered in the United States in 2002, and since then it has spread out from Michigan to many other states. For some years, the bug has threatened Maine from its New Hampshire and Quebec borders, where it has devastated ash trees there. The calm before the storm has passed, however, as the dreaded insect was identified in northern Maine just last month.

But Bath is ready.

“Over the past couple winters we’ve put a plan together,” said Bath City Arborist Kyle Rosenberg.

He noted that although the insects were just identified in Maine this year, due to their lifecycle they have likely already been in the state for a while.

“The state has been recommending not to take any action until it was officially found in Maine,” said Rosenberg.

One of the most successful ways to slow the spread of the insect is to simply stop transporting firewood.

“Through our everyday actions, when we take firewood from home to our campsite, mail a gift of homegrown fruits or plants, or order plants, seeds or fruit online, we can contribute to the unintentional spread of any number of destructive plant pests,” said State Plant Health Director Terry Bourgoin in a statement last year warning about the spread of the emerald ash borer. “So when people wonder if their individual actions really matter, the answer is yes.

“It only takes one person to move something they shouldn’t,” he continued. “We know the emerald ash borer beetle didn’t fly to New Hampshire on its own, it hitchhiked there. And now all of their urban, suburban and rural ash trees are at risk of attack by this devastating pest.”

Rosenberg credited more awareness and efforts to halt the transportation of firewood across state lines with slowing the emerald ash borer’s entry into Maine.

Still, the insect will inevitably spread by natural means as well, so the city must be prepared for the potential onslaught.

“It’s probably already here, it just hasn’t been found,” said Rosenberg.

The first step of the city’s plan is to identify the ash trees on or near city-owned land and plug them into the Bath City Tree Map, an online tool that maps out and identifies many of the trees on public land.

“Step two is to start removing trees that are either of poor quality or are already weak,” said Rosenberg, “and trying to test some of our larger ash trees.”

The weak trees will be replaced with trees of other species from the tree nursery the city launched just a few years ago. Rosenberg noted that they started the nursery with the emerald ash borer in mind.

Step three will be injecting ash trees with chemicals that will hold off the emerald ash borer until the borer, hopefully, moves on.

“Anecdotally, I hear from other folks who have already gone through the emerald ash borer that they sort of act like a locust,” said Rosenberg. “They’ll come and eat the resource and then once the resource is gone they move on.”

The village of South Barrington in Illinois has been under attack from the infamous beetle for years now, and has used injections to some level of success.

“I think we’ve been working on this since 2012, and what the mayor and board have decided to do here is try to treat the trees and keep them going as long as we can,” said Village Administrator Bob Palmer. “What we’re doing is treating them every three years.”

Palmer said the village of about 4,500 residents spends about $60,000 on treatment every three years. The village had about 830 ash trees in their municipal parkway to take care of 2012, and treats about 530 trees.

“It’s expensive,” admitted Palmer, who noted that municipal officials have to weigh the cost of treating trees versus removing and replacing them.

The village continues to lose some trees annually, and has lost an estimated 90 trees during the last several years. Palmer said he’s not sure if there’s an end in sight.

“I don’t know if any of these trees will be out of risk,” he said.

Bath’s efforts to remove trees and begin injections will begin in the next couple of seasons, said Rosenberg.

Removals will take place first, he noted, and injections will begin when the insects have been spotted closer to Bath. The best thing private property owners can do, Rosenberg said, is copy the city’s plan: Remove and replace weak trees now, and inject when the insects are in the vicinity. As the city arborist, Rosenberg is available to consult with property owners on what they can or should do to prepare for the emerald ash borer.

One way to identify a possible infestation is “blondeing,” said Rosenberg.

“That’s when the woodpeckers are trying to get the larvae underneath the bark they fleck off pieces of bark, and the new bark (underneath) is a different color,” he explained. “It’s a really good diagnostic tool.”

About 6 percent of inventoried trees in Bath are ash trees, which is slightly higher than the statewide average of 4 percent. For comparison, about 60 percent of inventoried trees in Bath are various species of maples.

nstrout@timesrecord.com

What they do

• An invasive species from Asia, the emerald ash borer has destroyed hundreds of millions of ash trees in 34 states in the past 15-plus years. The insect lays eggs in the tree’s bark, where they hatch and then bore into the tree to feed, before eventually emerging as adults and starting the process anew.