(Photo: Reed Galin/Lone Tree Productions)

In the last decade, tiny forest-dwelling beetles have wiped out pine trees on millions of acres in the Canadian and American West, including Southern California. The rest of the state has been largely spared, but forest ecologists say that’s likely to change.

Reporter Ilsa Setziol recently spent some time tracking these bugs with an entomologist from the US Forest Service. They found beetles at work in Jeffrey pines and coulter pines in the San Bernardino National Forest, east of Los Angeles.

You can hear her radio feature on The California Report, produced by KQED Public Media. She also put together a slide show, so you see for yourself how these tiny creatures — normally part of a healthy forest ecosystem — can, under the right conditions, quickly run amok.