Compositions and methods for controlling molluses, members of the Gastropodaand Bivalvia classes which includesbut is not limited to lactones, lactams, carbamates, amides, and/or carboxylicacid containing compounds as active ingredientsand/ or compounds derived from Pseudomonas and/or Erwinia. Also provided aremethods and compositions for increasingthe efficacy of chemical and biological control for invasive molluses in openwaters, power plants, and drinking water treatmentfacilities under coldwater conditions.