Diplostomum spathaceum (Rudolfi 1819), (Diplostomidae) the fish eye fluke which causes the disease diplostomatosis, was reported in Utah by the Division of Wildlife Resources in 1974. Previous to this date diplostomatosis was suspected to occur in three reservoirs in the state. Diplostomatosis, whi.ch is due to the presence of the metacercarial stage of this parasite, causes cataracts of the lens. The incidence of the disease in Utah has generated public and academic concern.