A rot grub is a small grub that eats rotten wood. They are often found in the bark of treants in the forest of Cormanthor where they help to combat the tube wilt by eating the rotten wood and the fungal infection that causes it.
References
- James Butler, Elizabeth T. Danforth, Jean Rabe (September 1994). “Cormanthor”. In Karen S. Boomgarden ed. Elminster's Ecologies (TSR, Inc), p. 27. ISBN 1-5607-6917-3.