CHAMPAIGN – Everyone knows a newspaper is "black and white and read all over." But what's purple, sticky and best when empty?
Nope, it's not a bottle of elderberry wine. The answer is an emerald ash borer trap, and 22 of them are hanging from ash trees in the Champaign-Urbana-Savoy area.
The Illinois Department of Agriculture plans to check the traps for the emerald ash borer, a beetle that's destroying the nation's ash trees. Thirty million trees in the Midwest have been killed so far, and this month the beetle was spotted in southwestern Bloomington, only 45 miles away from Champaign-Urbana.
The purple traps are about 24 inches long and have three sides. Manuka oil, which comes from a small tree in New Zealand, is used as a lure, and the traps are coated with nontoxic glue to capture the insects.
According to a Web site maintained by Maryland Cooperative Extension, the small, metallic-green beetles tend to be attracted to red and purple. The beetles' antennae seem to respond to manuka oil, which has four active compounds that also happen to be produced when an ash tree is stressed.
The traps in Illinois will remain in place throughout the beetle's flight season, which runs from May to August, according to the state agriculture department. About 2,700 traps have been placed in the 100-mile buffer zone surrounding the six counties in northeastern Illinois where the bug has been found.
The state will begin checking the traps Aug. 4, according to Juliann Heminghous, the department's outreach coordinator on emerald ash borers. The original plan was to check the traps throughout the flight season, but storms knocked down the traps, and it took time to replace them, she said.
The Bloomington trap happened to be checked by someone working in cooperation with the agriculture department, Heminghous said. That person had placed a trap for another exotic pest nearby, and when that was taken down, the emerald ash borer trap was also examined.
Now that the beetle's been found in Bloomington, the agriculture department plans to strip bark from ash trees within a half-mile of the site in hopes of determining the limits of infestation, she said.
The wood-boring bugs devour the layer under the ash tree's bark, disrupting the tree's ability to transport water and nutrients, according to www.illinoiseab.com , an agriculture department Web site devoted to the pest.
Champaign forestry supervisor Bill Vander Weit, who attended a meeting about the beetle Monday in Bloomington, said he has checked several traps in the Champaign area and seen no beetles. Plus, whenever city arborists remove an ash tree, they look for signs of emerald ash borer.
"So far, we've come up empty," Vander Weit said.
Many of the traps in the Champaign-Urbana area are near interstate exits and along well-trafficked roads – such as Mattis and Springfield avenues in Champaign and Florida Avenue in Urbana – in case the pest comes in on vehicles carrying wood products.
Eighteen counties in northeastern Illinois are under a quarantine preventing intrastate movement of wood products such as ash trees, limbs and firewood. There's also a federal quarantine barring the interstate movement of those products between Illinois, Indiana, Ohio and Michigan.
University of Illinois Extension entomologist Phil Nixon said that in addition to setting traps, the state has girdled ash trees — that is, removed a ring of bark from them — in an attempt to attract and detect the beetle.
"That's a more effective method, but it kills the tree and it's a lot more labor-intensive," he said.
Nixon said people who live near a trap don't have to worry about it attracting emerald ash borers to their neighborhood, because the beetle commonly flies no more than a half-mile during a flight season. The traps attract beetles only if they're already in the neighborhood, he said.
The beetles, first spotted in the Midwest in 2002, are thought to have come into the Detroit area when wood products were shipped there from Asia. The bug has since spread from Michigan to Ohio, Indiana, Illinois, Maryland and the Canadian province of Ontario. The first spotting of it in Illinois came in 2006, when it was found in Kane County.
Emerald ash borer infestation symptoms
— D-shaped exit holes in bark.
— S-shaped tunnels on surface under bark.
— Sprout growth at tree base.
— Unusual activity by woodpeckers.
— Die-back on top third of tree.
— Vertical splits in bark.
Trees with two or more symptoms should be reported to the county Extension office or the Illinois Department of Agriculture.
Source: Illinois Department of Agriculture