Description: Metacercaria stage as described by Hughes, 1927: Strigeid metacercariae with both fore- and hind-bodies well developed and distinctly set apart by a constriction; no lateral sucking-cups; fore-body leaf-like; hold-fast organ well developed; reserve bladder highly developed, the smaller branches of which are usually anastomoses; calcareous granules mostly free in the circum-ambient fluid; encysted.
Life Cycle: “Eggs are released by fish-eating birds into the water. Eggs develop into intermediate stages of the parasite in snails. These free-swimming parasites penetrate the muscles of fish and encyst. Black pigmentation is deposited onto these cysts. Infected fish are consumed by birds where the life cycle starts all over again. Adult worms are seen in fish-eating birds” (MN Dept. of Natural Resources).
Sources: MN Dept. of Natural Resources. http://www.dnr.state.mn.us/fish_diseases/neascus.html Accessed January 22, 2016