Brood X Periodical Cicada (IMAGE) Entomological Society of America Caption A long-standing query about periodical cicadas that emerge every 13 or 17 years was recently answered by a team at USDA Agricultural Research Service: Once periodical cicadas emerge, do they actually feed on vegetation? Their analysis of cicadas' gut contents found plant DNA in mature adult cicadas but none in freshly emerged adults, a strong sign that adult cicadas do feed on plants, since no plant matter in cicadas' guts carries over from their nymph stage. Shown here is a Brood X 17-year cicada adult on a linden tree leaf in Maryland during the brood's 2021 emergence. Credit Peggy Greb, USDA-ARS, public domain image Usage Restrictions No restrictions. License Public Domain 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.