Guerra (IMAGE) University of Cincinnati Caption UC biologist Patrick Guerra studies the multi-generational migration of monarch butterflies. He found that light pollution near places where butterflies are resting at night can interfere with their internal compass, making the butterflies think it's earlier or later in the day than it really is. Credit Lisa Ventre/UC Creative Usage Restrictions None License Original 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.