Distribution of potential intermediate hosts for Fasciola hepatica and Fascioloides magna in Montana, USA

A collection of lymnaeid snails in Montana, USA, was made over a 3 year period, in conjunction with a state-wide survey of the distribution of liver flukes. Collection areas were selected based on reports of infected cattle, sheep or wildlife, and with the intent of covering all geographical regions of the state. Snails were found at all 97 of the locations selected for collections, and Lymnaeidae were collected at 71 of the locations. Nine lymnaeid species were collected, 5 of which have been reported either as natural or experimental intermediate hosts for Fasciola hepatica or Fascioloides magna. The 2 species most widely distributed over the areas enzootic for the flukes were Lymnaea modicella and L. caperata..