The floating aquatic fern, Salvinia molesta D.S Mitchell (Salviniaceae) was first recorded in Senegal in 1999 and by 2000 it covered an estimated area of 18 000 ha on the Senegal River Left Bank and tributaries (Senegal) and 7840 ha on the Senegal River Right Bank (Mauritania). The weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae) was considered the best option for control and some 48 953 weevils were released at 270 sites during 2002. Within one year, weevils had established and were recovered up to 50 km from the release sites. At most of the release sites, the S. molesta infestation was reduced from 100% to less than 5% within 24 months of release. These results are discussed in the context of the weed's negative impact on aquatic systems.