WEST LAFAYETTE — They're coming back and they're hungry for ash trees. Emerald ash borer, an invasive insect that feeds on North American ash trees, will begin flying again in the state of Indiana in May. With the re-emergence of this invasive pest, Purdue University experts are advising ways people can help slow its spread.

"One of the biggest issues we've seen with emerald ash borer (EAB) is campers unsuspectingly spreading the insect by transporting firewood from place to place," Purdue entomologist Jodie Ellis said. "It is of utmost importance that firewood is purchased and burned completely at the camper's destination."

Beyond avoiding firewood movement, Indiana residents should be sure they are following township and county wood quarantines.

"In areas where EAB infestations have been confirmed, no ash products should be moved out of the infested township," Ellis said. "In addition, no ash products should leave the county either. These quarantines help slow the insect from spreading into unaffected areas."

Indiana currently has 17 counties with confirmed infestations, including Adams, Allen, DeKalb, Elkhart, Hamilton, Huntington, LaGrange, Marion, Noble, Porter, Randolph, St. Joseph, Steuben, Wabash, Wells, White and Whitley. A large portion of Ohio that borders Indiana to the east now has confirmed infestations as well.

In some areas where emerald ash borer is confirmed, residents have faced some additional challenges - including scammers.

"We want to make sure consumers are educating themselves about their options if emerald ash borer is found in their areas or on their properties," Ellis said. "If someone knocks on your door and says you have an infestation, make sure you do your homework before having the tree treated or removed.

"While the tree may appear to be infested with larvae under the bark, it's important to realize that other non-harmful insect larvae live under the bark of ash trees. This doesn't necessarily mean an EAB infestation is present."

Emerald ash borer is difficult to detect, and only trained professionals will have that ability, Ellis said.

"If you're not sure whether your tree is actually infested, call Purdue Extension or the Indiana Department of Natural Resources (IDNR) and get an expert's advice on how to proceed," she said. "If an infestation is confirmed, you have more than one option. Although it might be a good idea, you are not required to have that tree removed. In some cases an infested ash tree can be treated and can recover."

Purdue Extension can be reached by calling (888) EXT-INFO, or Ellis can be contacted directly at (765) 494-0822, ellisj@purdue.edu. The IDNR has an exotic species hotline where emerald ash borer information can be obtained by dialing (866) NO-EXOTIC (663-9684).

Additionally, Purdue's emerald ash borer Web site with up to date information can be found at http://www.entm.purdue.edu/eab. The site also contains a link to the page in Spanish.

Since its discovery near Detroit in 2002, emerald ash borer has destroyed millions of ash trees in seven states, thousands of these trees have been in Indiana.