The fresh water mollusc,
Lymnaea tomentosa, the intermediate host of the liver fluke is heavily infested under natural conditions with ectocommensal annelid,
Chaetogaster limnaei. These annelids which destroy the larval stages of
Fasciola hepatica have been observed in the laboratory. The association of
C. limnaei with the snail intermediate host is of value in exploiting a control measure against economically important liver fluke disease.
I am greatly indebted to Dr. M. J. Howell for his critical comments and help in preparing this research note. Also to the Australian National University authority for awarding a scholarship to carryout this work.