Green, Red and Gray Trees (IMAGE) U.S. National Science Foundation Caption Trees go from green and healthy, to red and dying, and finally to gray and dead, from bark beetles. Credit Lindsay Bearup 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.