The tropical American shrub Clidemia hirta (Koster's Curse) has become a pest in pastures, cropland, and forests, where it has become naturalized in many parts of the humid tropics. It has spread through the island of Oahu, Hawaii, since 1941, despite attempts at biological control by the introduction of the parasitic thrips, Liothrips urichi, which had proven effective in supressing growth of this noxious weed in Fiji.
The pest has colonized habitats similar to those occupied over its natural range—such as forest clearings, trail-sides, and burn-sites. In addition, in Hawaii it has intruded into the understorey of forests which were formerly free from exotic weeds. Fears are held that the resulting ecological disruptions may place further stress on the frail island ecosystems and cause plant and animal extinctions while producing other management and aesthetic problems.
Immediate action is necessary to eradicate small colonies of Koster's Curse that have become established on near-by islands, and recommendations are made regarding efforts needed to devise means to control heavy infestations in the highly inaccessible mountains of Oahu.