FLAGSTAFF — As flurries started to descend on the forest floor, a team of researchers examined a stand of sickly quaking aspen trees off U.S. Highway 180, just north of Flagstaff. To an untrained eye, the trees might have looked normal. But up close, the picture was different: The usually matte white bark was covered with thousands of tiny dark notches, giving the trunks a dull appearance, darkened, almost black.
Kristen Waring, a professor of silviculture and applied forest health at the School of Forestry at Northern Arizona University, knew what to look for. She and two graduate students, Connor Crouch and Kelsey Pemberton, quickly pinpointed problem areas.
What looked like an inanimate object was actually a tiny, sap-sucking insect called oystershell scale. Its diminutive size belies the greater threat it poses to aspens and trees throughout Arizona. Colonies of the invasive creatures can encase mature trees, leading to fatal infestations. Eventually, oystershell scale populations can balloon to the point where they can kill entire stands of trees...