Park rangers in the field (IMAGE) Florida Museum of Natural History Caption Butterflies aren't just restricted to ground level. To sample species that fly in the canopy, park rangers use a large sling-shot to place strings for bait traps in the tops of trees. Credit Photo by Maria Checa Usage Restrictions Credit must be given to the creator. License CC BY 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.