Fish-eating bird, primary host. Adult grub lives in mouth and throat. Mature egg 6. Life History of the Black Spot parasite 1. Snail, first intermediate host.
Larval grub makes several changes of form in snail.
Fish, second intermediate host. Grubs encyst under skin, causing black spots to form. Fish-eating bird, primary host. Adult grubs live in intestine. Eggs pass out with body wastes.