Mating fruit flies (IMAGE) University of Groningen Caption This picture shows two fruit flies mating. The scientists in the study observed and registered thousands of matings to study mate preference. Credit Billeter Lab, University of Groningen Usage Restrictions With credit 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.