Oviposition behaviour of Lymnaea truncatula in central France

Several authors have reported on the annual generations of Lymnaea truncatula in the field or under laboratory conditions,--and the morphology of the egg masses has been described by Bondesen. Still unknown are some parameters of reproduction under field conditions, such as the length of the oviposition period and fluctuation in the density of egg masses during this period, the number of eggs per mass and fecundity. Data about these aspects were obtained in 1995-1996 at 4 stations in central France (Fig. 1):