Trees Lightning Prime (IMAGE) Dartmouth College Caption Researcher Sharon Martinson, Dartmouth College, studies bark from beetle-attacked trees in Louisiana to determine why bark beetle population outbreaks occur. Credit Matt Ayres Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.