Ants cleaning their nest (IMAGE) Institute of Science and Technology Austria Caption Ants clean their nest box with formic acid. Special paper that turns pink on contact with acids was used to see when and how much formic acid the ants spray. Credit Christopher Pull Usage Restrictions None 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.