DANVILLE — Danville has officially joined Champaign-Urbana and other central Illinois cities in the battle of the emerald ash borer.
Since 2002, the invasive beetle, also known as EAB, has killed millions of trees as it's slowly marched south from the upper Midwest. So it was no surprise when an Illinois Department of Agriculture worker discovered infected ash trees in Douglas Park a few weeks ago — the first known infestation in Vermilion County.
"It wasn't a matter of if, but when," said Steve Lane with the parks division.
Lane's only surprise: that the county's first sighting didn't happen in Kickapoo State Park, with its campground that draws visitors and firewood that comes from outside the area.
The small, green metallic-colored insects, which are native to Asia, were first discovered in the United States 12 years ago in Detroit. They were likely transported in wood packing material, according to the U.S. Department of Agriculture.
The beetles slowly spread south — through the transfer of firewood, experts believe.
Douglas Park is close to I-74 and a gas station. Lane said the ash borer may have hitchhiked on firewood or brush from a vehicle exiting the interstate.
"The goal is to slow the spread and minimize the impact," said Lane, who put together a management plan for the city with an inventory that shows 317 ash on city property. The trees have grown well in the city's environs through the years, according to Lane — some reaching 100 feet tall.
Three city parks — Garfield, Cannon and Meade — have high concentrations of ash. Garfield leads the way with 17, representing 40 percent of the park's trees. And the city's golf course, Harrison Park, has 38 ash.
But one of the highest concentrations is in the first two blocks of North Vermilion Street, the city's downtown business district, where 21 ash constitute half to two-thirds of the tree-scape.
City officials don't know how many more ash trees are on private property.
According to Lane's report, opinions vary on the effectiveness of chemically treating ash trees, but the city will use insecticide only on young, healthy trees that are part of designed plantings. The city has already identified 73 trees for treatment with a soil-drench chemical. The annual cost: less than $1,000.
Danville's plan also will include removing trees that show two or more signs of infestation, as well as those that are already unhealthy or in poor condition. Any replacement of ash trees will occur only as city funds allow.
Two years ago, the emerald ash borer showed up in Champaign, where city officials have increased tree removal efforts and budgeted $270,000 over four years to battle the beetle. It threatens 1,994 ash trees on public property in Champaign — and even more in parks and on private property.
The adult beetles emerge in May and June, and the females lay eggs in the bark of ash trees. The larvae hatch and bore into trees, cutting off its water and nutrients. The adults leave D-shaped holes in the trunk or branches as they exit, but sometimes those aren't noticeable until the bark is removed.
The beetles were first discovered in Illinois in 2006. Now more than 40 counties in the state — including Champaign, Ford, Iroquois and Vermilion — are part of a quarantine, restricting movement of firewood and brush. The city of Danville cannot take down or treat ash trees on private property, so officials encourage residents and business owners to contact tree professionals.
Sandy Mason, a horticulture educator with University of Illinois Extension, said private property owners don't have to do anything right away, other than making sure their trees truly are ash. Then, they must decide whether the trees are integral to the property. (For instance, the patio is built around one). If they are, there are treatments available.
"Some can be pretty effective," said Mason, adding that it depends on tree size. The larger the ash, the less effective the chemicals.
Do-it-yourself treatments must occur every year, Mason said; treatments professional arborists can be every other year.
If the ash tree isn't integral to the house or property, homeowners can just wait and see, Mason said.
"It may very well get the insect eventually, and they can take the tree down at that time," she said. "If it's a tree that's not looking all that good anyway, they can take it down now."
4 things to know about emerald ash borer:
1. If your ash tree shows woodpecker damage, it's a bad sign. The tree trunk-tapping birds like emerald ash borer larvae.
2. Another sure sign of infestation: the presence of adult beetles. They're metallic green and about a half-inch long.
3. Adults leave D-shaped exit holes in the bark when they emerge in spring.
4. Firewood cannot be moved outside of many states, including Illinois, because of a federal quarantine.