Eggs of Bothriocephalus opsariichthydis YAMAGUTI, 1934 were collected by dipping its gravid proglottides into sterilized water. The eggs were ovoid and measured 42-57×33-40μ. They had thick, slightly adhesive shells of about 1μ thick and contained no oncospheres when expelled from uterus. The coracidia were hatched out mostly between 2 to 5 days at 25deg;C, but not at 37deg;C and 15deg;C. Light was not needed for hatching. The coracidia were spherical and had cilia of 12-20μ long on the surface. They measured 18-24×15-23μjust after hatching and were enlarged to 76×73μto 107×96μafter 6 hours. Since the embryos die rapidly at 2-7deg;C, it is assumed that the eggs are unable to survive the winter in the pond.
It was confirmed by experiment that the eggs of Bothriocephalus opsariichthydis YAMAGUTI, 1934 collected artificially were killed rapidly by drying, freezing, and ultraviolet rays. Eleven chemicals were tested for ovicidal effect. Among them two chlorine compounds were found to be effective; that is, 3.1 ppm of sodium dichloroisocyanurate and 9.0 ppm of higher bleaching powder killed all eggs.