The treated habitats have not been recolonized by Lymnaea truncatula . Four aquatic snail species showed an increase in their numbers: L. glabra in the stations of Haute-Vienne, L. glabra, Physa acuta, P. hypnorum and Planorbis rotundatus in the habitats of Indre. The numbers of L. glabra and P. acuta reached their maximum on the third year and decreased thereafter; those of P. hypnorum and P. rotundatus slightly increased from the fourth or the fifth years treatment. The colonization of L. truncatula habitats was incomplete and did not reach over 50% of the surface for L. glabra and P. acuta , 20% for P. hypnorum and P. rotundatus . The bivalve Pisidium casertanum did not recolonize treated habitats. There were no modifications in the numbers of hygrophilous terrestrial molluscs during the five after-treatment years when compared to control stations.