If you have an ash tree in your yard, now is the time to begin checking it for emerald ash borers in the adult beetle stage according to University of Illinois Extension entomologist Phil Nixon. "May 20 to 26 has been selected as Emerald Ash Borer Awareness Week because it coincides with the time of year that the adult beetles will begin to emerge."

How to identify the emerald ash borer beetle:

-- bright metallic emerald green color

-- half an inch long, bullet-shaped body

-- exit holes in bark shaped like the letter "D"

"There are a number of look-alikes that people might mistake for the emerald ash borer," said Nixon. "The tiger beetle, ground beetles, even some bees and wasps have the green color. Other borers make an oval or round exit hole. The "D" shape is distinctive. It's made by the shape of their body coming out of the tunnels in the bark -- perfectly flat on the bottom and rounded on the top."

In 2006 the beetles were spotted at ten sites in Kane County and six sites in northern Cook County in Illinois.

Insecticides containing imidacloprid have proven to be effective in preventing the ash borer from taking up residence in ash trees. The only brand currently available to homeowners is Bayer Advanced Garden Tree and Shrub Insect Control. Others can be professionally applied.

But, Nixon said that the best way to prevent infestation of the emerald ash borer is to purchase only local firewood and if you go camping, don't transport any left-over firewood. Leave it at the camp site.

The emerald ash borer was first identified in ash trees near Detroit in 2002 and has spread to neighboring states since then, most likely via packing materials and firewood. The larvae winter-over in the bark. Adult beetles emerge from the wood during May and June, then go on to infest a new neighborhood of unsuspecting ash trees.

Nixon said that, on their own power, the beetles only travel about half a mile a year. As with many other invasive species, with assistance from humans, the emerald ash borer can travel much greater distances and infest ash trees just about anywhere.

For more information, visit www.emeraldashborer.info/ or www.ipm.uiuc.edu.