Biology
Eggs seen inside the segments of Hymenolepis microstoma. © L Cunningham & PD Olson
Size
Worms vary from 4 to 30cm in length, depending on the age and number of worms within the host.
Hymenolepis species and other tapeworms often exhibit a ‘crowding effect’ in which the total biomass of the worms stays more of less constant, regardless of the intensity of infection. Thus low intensity infections result in larger worms and high intensity infections produce smaller worms.
Under laboratory conditions, H. microstoma adult infections in mice are typically limited to approximately 12 worms.
Growth
Larval metamorphosis in the intermediate host takes 7--10 days.
Juvenile worms establish in the bile duct of mice after approximately 3 days movement within the upper GI tract (small intestine).
Once established in the bile duct, the worms then mature sexually and begin producing eggs within approximately 1 week.