Samoa introduced the New Guinea flatworm in the 1990s to curb crop-damaging giant African snails, but it also preyed on native land snails. Studies recorded releases on Savai‘i in 1996–98 and 2001, and concluded the predator had reached Upolu by the late 1990s.
The flatworm is a generalist predator that can move along the ground and up vegetation; researchers documented declines in partulid tree-snail populations where it was present. The U.S. Fish and Wildlife Service lists it as a threat to native land snails and says some Pacific island snail losses have been linked to it. The article cautions that some Samoan snail populations were already declining and habitat change may also have played a role.
Other Pacific islands also introduced predators, including Euglandina snails, to control giant African snails. These efforts often did little to curb the pest and instead added to declines and extinctions of endemic snails.
