Roach Aggregation (image) North Carolina State University Share Print E-Mail Caption This is an aggregation of German cockroach nymphs. Gut bacteria play an important role in how roaches gather together, according to new research published in PNAS. Credit Ayako Wada-Katsumata, NC State University 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.