Diplostomulum sp.

Adults of most species in this genus are found in the guts of birds.  Eggs are passed in the bird's feces, and snails serve as the first intermediate host.  The second intermediate host (most often a fish) is infected by the cercariae, and the resulting stage is called a "diplostomulum larva" (a metacercaria).  The avian definitive host is infected when it eats an infected second intermediate host.

A diplostomulum larva (metacercaria) from the eye of Ictalurus sp.


An adult Diplostomulum.  The expanded forebody (anterior end) is at the left of the image.  Original image copyrighted and provided by Dr. A.W. Shostak, and used with permission.