Ash borers hit trees in nearly half of Indiana

Metro-area residents are bracing for an invasion by a pest that is now on Indianapolis' doorstep after having already killed nearly a third of the state's ash trees.

Hancock County is one of four new Indiana counties where the emerald ash borer's presence has been confirmed. Since it was first spotted in the northeastern part of Indiana in 2004, the destructive beetle has now made a home in 42 counties -- nearly half of the state -- the Indiana Department of Natural Resources said Tuesday.

Twenty percent to 30 percent of the state's 153 million ash trees have been infected by the Asian beetle or are already in the process of dying from the infestation, the DNR said.

The ash borer is a dark metallic green beetle that is one-third of an inch in length and one-sixteenth of an inch in width.

Native to China, the beetle first made its way to the U.S. in wood-packing material in the late 1990s and was spotted in the Detroit area in 2002.

The adult beetles burrow underneath the bark of the ash tree, where they feast on nutrients through the tree's vascular system, an action that cuts off the tree's food and water supply and causes it to starve and die. The beetles also are busy laying their eggs underneath the tree's bark in May and June.

Most cases of emerald ash borer disease aren't spotted until the third or fourth year after the infestation, when symptoms of the ailing tree become visible, such as dead branches at the top of the tree. The tree usually dies within five to eight years after the initial infestation.

Allen and Huntington counties already have seen tens of thousands of ash trees die from the disease. In Carmel and Fishers, the crowns of many ash trees already are empty, a clear sign that the disease has taken hold -- and a grim foreshadowing to what could happen to trees in the rest of the metro area.

The fight

Philip Marshall has fought off a lot of insects in his 37 years with the state, including the bark beetle, which helped spread Dutch elm disease in the 1970s, and the gypsy moth, which is attacking the state's oak trees. His forecast for the future of Indiana's ash trees is grim.

"It'll take years for the trees to succumb to the emerald ash borer disease, and it'll take many more years for it recover and come back," said Marshall, the director of Indiana's Entomology and Plant Pathology Division.

The numbers of infected ash trees make up only about 2 percent to 3 percent of Indiana's more than 2.3 billion trees.

However, when considering the concentration of ash trees in the state's urban and suburban communities -- and the aesthetic appeal of the trees -- the scope of the destruction becomes more alarming.

Going as far back as the 1970s and '80s, developers brought millions of ash trees to many of Indiana's urban neighborhoods. Those trees not only provided picturesque canopies of cooling shade but added value to a homeowner's property by providing an energy savings.

For example, an ash tree with a 24-inch diameter can earn the average homeowner $212 a year from savings in heating and cooling, according to an online U.S. Forestry Service tree benefits calculator.

Indianapolis' Downtown is believed to have a little more than 10,700 ash trees out of 100,000 total trees.

The city has partnered with two out-of-state companies to collectively treat 122 trees at Martin Luther King Memorial Park, Holliday Park and Broad Ripple Park. Thus far, the city has removed only 17 trees because of emerald ash borer disease and has plans to remove 24 more ash trees in the near future.

The city could choose to spend $3.22 million over the course of 10 years to treat its ash trees, according to the Purdue emerald ash borer cost calculator provided by Cliff Sadof, a professor of entomology at Purdue University.

Or the city could spend $3.04 million to remove the trees and another $1.98 million to replace the trees, the Purdue calculator said.

Back in 2005, the DNR was provided $2 million through a federal grant to eradicate the emerald ash borer through removal of the trees. Now the state has shifted its plans from eradication to containment within the affected counties; the DNR is spending about $135,000 from another federal grant to identify and contain the disease, as well as for education and outreach services.

A natural enemy

But there may be another solution to the problem.

The state's hope of containing the emerald ash borer now rests with another Asian insect, a stingless parasitic wasp that feeds off the beetle.

The U.S. Department of Agriculture has allotted about 20,000 wasps to be planted in parts of Indiana, as well as seven other states, in hopes of controlling the beetle.

"Right now the emerald ash borers are like kids in candy stores going wild," said Jodie Ellis, the exotic insects education coordinator at Purdue's entomology department. "It's very good news to introduce these wasps, but the problem is that those populations take a long time to build an effect."

The emerald ash borer has a short range, traveling less than two miles in its short, one-year lifespan from egg to adult.

The biggest reason why the disease has spread so fast is the movement of firewood through multiple states and counties.

"The vast majority of all our detections that have been positive are all related to firewood," Marshall said.

The ash borer will often crawl out of firewood cut from an ash tree and search for the next tree to feast on, thus spreading the disease.

For homeowners who have ash trees in their yards, it is strongly recommended that they treat the trees with an insecticide that kills the emerald ash borer and protects the tree.

"If you have an ash tree and you don't treat it, it's going to die," said Sadof, the Purdue professor. "If nothing is done, you might see entire blocks or groups of trees that are dead in the middle of summer. It'll look like winter."