Ash borers' favorite meal to slowly fall off the menu?

Efforts to stop the regional spread of the emerald ash borer - which was found last month to have reached Schaumburg - are meeting with only limited success.

But one consequence of the insects' voracious appetites and ever-increasing reputation is that they may end up stopping themselves.

Schaumburg Public Works Director Steve Weinstock said many people are quite naturally choosing other species of tree when planting new.

Dave Nelson, a volunteer in the plant clinic of Morton Arboretum in Lisle, said the arboretum is actively advising people to choose other trees for the time being.

The combination of the ash tree's appearance and hardiness made it ideal for urban and suburban environments, Weinstock said. Not only does it grow relatively quickly, but it's especially resistant to pollution and road salt runoff.

But there are about 30 other species that could reasonably be substituted, and which may bring the added benefit of eradicating the near monoculture of ash trees that has evolved, he added.

About a third of Schaumburg's 36,000 publicly owned trees are ash trees. Last month's discovery of eight damaged trees near Syracuse Lane and Walnut Court in the southwestern corner of the village revealed an infestation that was probably about four years old, Weinstock said.

One of the problems of early detection is that the insects typically infest the upper parts of the tree, and the damage caused by the larvae can be subtle for the first few seasons.

But eventually, the larvae do enough damage to the circulation systems of the trees to kill them entirely.

"There is no cure for this," Weinstock said. "If the trees are attacked, these borers destroy their hosts."

Even the most effective solution isn't guaranteed to work, in addition to being expensive and labor-intensive. It involves using a chemical on the root system of a tree every year which is supposed to make it toxic to the larvae.

The only ash tree that's immune to the insects is the mountain ash, which is really an entirely different kind of tree from the white ash and green ash despite their similar names, Nelson said.

Morton Arboretum appears to have stayed free of the emerald ash borer, but that may be because it doesn't suffer from the same monoculture as do residential areas of the state, he added.

When the Asian insects made their first American appearance in Michigan in 2002, officials tried to stop the spread there by clear-cutting a two-mile radius around infected areas.

Illinois officials today at least have the benefit of knowing such an extreme measure was ineffective. The plan in Schaumburg and many other areas is simply to respond to damage as it occurs, and replace trees with different species, Weinstock said.

The Illinois Department of Agriculture has advised municipalities to expect an annual tenfold increase in damaged trees in affected areas. Eight damaged trees this year could mean 80 next year and 800 the next.

The dead trees can be safely shredded into mulch, however, as the dimensions of each wood chip are too small for ash borer larva to survive, Weinstock said.