TOLEDO, Ohio (AP): Researchers studying a tree-killing beetle are asking folks in northwestern Ohio and southeastern Michigan to help them with a scavenger hunt of sorts.

The scientists think there are few ash trees out in the woods that have been able to withstand the emerald ash borer.

They hope to find those surviving ash trees and figure out why they were able to fend off the destructive beetle.

The Blade newspaper in Toledo reports that researchers are focusing on northwestern Ohio and southeastern Michigan, because that's where the ash borer first took hold in the U.S.

The beetle came from Asia and arrived in the U.S. around more than a dozen years ago. It has since killed about 50 million ash trees in the Upper Midwest.