Monarch Caterpillar (image) University of California - Berkeley Share Print E-Mail Caption A monarch caterpillar. Caterpillars eat and store the toxic compound in milkweed to deter predators. The toxins are retained through metamorphosis, making the butterfly toxic as well. Credit UC Berkeley photo by Noah Whiteman Usage Restrictions None Share Print E-Mail 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.