In order to control the spread of the invasive Caulerpa taxifolia (Chlorophyta) in the Mediterranean, in situ experiments were conducted with the specialized predator Lobiger serradifalci (Mollusca: Ascoglossa=Sacoglossa). An unexpected effect of L. serradifalci on C. taxifolia was observed. Instead of destroying the algal frond, the ascoglossan cut fronds into tiny living fragments capable of regenerating. Thus, L. serradifalci may facilitate C. taxifolia dispersal instead of controlling it.