Miracidium of Fasciola hepatica. The miracidium hatch from the egg when exposed to the appropriate warm temperature, moisture, light, and salinity. Using the cilia that cover its ectoderm, the miracidium will swim to find an appropriate host and bore its way into the snail, shedding its cilia and becoming a sporocyst as it enters.
Adult Fascioloides magna adults in situ and removed. Fascioloides magna may infect wild ruminants, cattle, sheep, and pigs; wild ruminants such as white-tailed deer act as a definitive host with patent infections. All others result in encapsulation of the adult fluke or extensive migration until host death. On examination of the liver of a definitive host, capsules in the parenchyma will contain two or occasionally three flukes.