The adult worms primarily live in the bile duct, gall bladder, and sometimes in the pancreatic duct. Although they are hermaphrodites, reproduction is by cross fertilization (two individuals exchanging their gametes). Fertilized eggs are laid in the bile duct and are discharged along the bile juice into the intestine, and finally released in the environment along with the faeces. An individual fluke may shed as many as 200 eggs in a day. The exact lifespan is not known, but is estimated to be more than 25 years.