Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Epifluorescence micrograph of green fluorescent protein-labeled Xenorhabdus nematophila bacteria being released from the intestine of an infective juvenile-stage Steinernema carpocapse nematode. The nematode sheds bacteria by defecation in response to infecting an insect host. As seen in this image, released bacteria collect in a loose outer membrane that surrounds the nematode. The composite photograph was artificially colorized by using Metamorph 4.5r6 software and assembled in Adobe Photoshop 6.0.1. Magnification, x600. (See related article on page 3147.)