Gall Inducing Fly (IMAGE) Penn State Caption Goldenrod can detect a compound produced by gall-inducing flies, according to researchers. Credit Nick Sloff, Penn State Usage Restrictions Non commercial use only 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.