Juvenille Gnathiids Engorged with Fresh Blood (image) National Science Foundation Share Print E-Mail Caption These are juvenile gnathiids that have recently fed on fresh blood. Only juvenile gnathiids are parasitic. Credit Ann Marie Coile, Department of Biology, Arkansas 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.