Caterpillar attack alarm (IMAGE) University of California - San Diego Caption Researchers have identified the first key biological switch in plants that sounds an alarm following attack by animals such as leaf-munching caterpillars. Credit Schmelz Lab, UC San Diego Usage Restrictions Must be used in conjunction with PNAS paper on plant receptors. 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.