Beetle (IMAGE) DOE/Argonne National Laboratory Caption X-ray imaging of beetles helps confirm that tracheal system design may limit size in insects. More of the body is filled with air-filled tracheal tubes in larger species, particularly in the legs, and so much larger species than exist today might not have room for enough tubes. Credit Argonne National Laboratory 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.