Emerald Ash Borer moves into Littleton, could destroy 15% of urban canopy in Denver metro area

Littleton has detected the Emerald Ash Borer in at least one tree in town. The beetle is a non-native pest that has the potential to dramatically change the landscape of Colorado's Front Range.

"One in five trees could be wiped out by this pest if people aren't preventative with treatment and getting ahead of it," said Michael Sundberg, district manager for The Davey Tree Expert Company. "They do a lot of tunneling under the bark and damage the tissue that carries the water and nutrients around the tree. It's kind of like the trees' veins, so to speak, that get attacked."

The City of Littleton said in a tweet that 15% of Littleton's trees are ash trees. If not properly treated, they could destroy 15% of our urban canopy. 

"The reason it's a big problem is that it's an introduced pest. It doesn't have any natural predators here, but overseas it might be kept in check and there are not as many ash trees. But for us, ash has been heavily planted for the last 40 years so they're everywhere. So you have a high food source, nothing to really slow it down and it's just a bad combination for a bug to just run wild and go crazy," said Sundberg.

Arborists recommend using pesticides to treat ash trees before a possible infestation because once beetles attack, it's likely the tree will die and have to be cut down. 

"It's best not to move around firewood. Not traveling logs around is where you keep it from spreading fast from city to city. The bug can fly, but not super far… when it comes to jumping, I think they found it in Carbondale. The bug didn't fly to Carbondale, it hitched a ride on some logs," said Sundberg. 

Experts say Emerald Ash Borers leave a distinctive "D" shape marking on the bark. Another sign is more activity around the roots, like a lot of sucker sprouts and not much growth up top. 

"When it comes to the urban canopy here it's super worrisome because we have too high of a population of ash trees… and unfortunately, not enough people are going to treat to keep them around. Your neighborhoods will change from being shaded and nice to having no trees, or new trees again," said Sundberg.

Arapahoe County is prioritizing ash tree insecticide treatments and removal and there are some programs to help residents with the cost. Residents should contact their local municipality for information and resources: 

• Littleton
• Englewood
• Greenwood Village
• Centennial 
• Cherry Hills Village
• Lone Tree
• Arapahoe County

The Emerald Ash Borer isn't the only wood-boring insect hurting Colorado trees, Colorado State University Extension shows how to tell the difference between these pests and how to help prevent their spread.