Originally from Asia, emerald ash borers spread through infested wood that’s transported. Burn infested wood to destroy the borer’s eggs and larvae.

Thousands of colorful ash trees in Lawrence could be at risk of becoming piles of firewood, or worse, as a tree-destroying beetle works its way toward Douglas County, the city’s top horticulturist said.

The insect that arborists and others are keeping an eye on is the emerald ash borer. It has made its way to the Kansas City metro area, and Crystal Miles, horticulture manager for the city’s Parks and Recreation Department, said the beetle is expected to show up in Douglas County in the next one to two years.

When it does, Lawrence’s tree landscape may look quite a bit different.

“It will be highly, highly noticeable on the trees that it takes,” said Mark Hecker, the city’s assistant director of parks and recreation. “We easily have 3,000 to 4,000 ash trees in Lawrence.”

Currently, Miles said there is no way to prevent the ash borer from attacking a tree. There are some pesticide-based treatment methods available once a tree has been infected, but they could require about a $100 treatment every one to two years for the life of the tree.

“It will be a challenge,” Miles said. “We’ll really have to prioritize what trees we want to save.”

Miles said a preliminary inventory shows that there are a little more than 1,000 ash trees in city parks and right-of-ways. Miles’ office is working on a draft plan of how to proceed once the ash borer arrives in the city. One option is to try to keep healthy ash trees that are larger than 8 inches in diameter but less than 20 inches in diameter. Other ash trees not meeting that criteria would be removed to help prevent the spread of the insects. Based on current numbers only about 100 of the 1,000 city-owned ash trees would meet the criteria to be saved.

A final determination on how the city will deal with the issue likely won’t come for another few months, and may end up being a budget issue for city commissioners this summer. Miles is estimating the city may need to spend more than $90,000 a year just to treat trees, remove trees and plant new trees as a result of the disease. The costs likely will grow beyond that because the city and county probably will be required by state regulators to create a quarantined wood lot to properly dispose of the diseased trees.

Homeowners who have ash trees will have to make their own determinations about whether to try to save a tree or remove it. Parks and recreation officials said tree owners should count on having to deal with the insects.

“We know they’re coming,” said Ernie Shaw, the city’s leader of parks and recreation. “We just don’t know when.”

The ash borer already is active in at least 20 states and is expected to change the landscape dramatically in some.

“I’ve been to conferences where they have said if you haven’t been to the Smoky Mountains, you had better go now because in 10 years it will be a completely different landscape,” Shaw said.

The disease wasn’t on the radar of American arborists decades ago when ash trees were being recommended as a good tree to plant in Lawrence because of its resistance to drought. The ash borer is native to parts of China and Russia, and it first was introduced in America in 2002. The current thinking is it came over in wooden shipping pallets.

Once they arrived in America the insects spread by flying, attaching to vehicles or being transported in firewood or other wood debris, Miles said. The state’s Department of Agriculture has instituted certain quarantines that have prevented live ash trees from being brought from out of state, and also more localized quarantines in the Kansas City metro area that are designed to stop ash material from those counties spreading to other Kansas counties.

When a tree is infected, it often starts to show signs of twig die-back in the canopy or other branches of the tree, and signs of exit borer holes also may be evident on parts of the tree.

City officials said there are ash trees in virtually every part of the city, and they certainly have been popular trees in several city parks.

“There are probably 10 of them in South Park alone,” Hecker said. “It is something we’re definitely going to have to think about.”