Petroleum ether (PE) and chloroform (C) soluble fractions of methanolic extracts of nine different macrophytes viz. mangroves (Derris heptaphyla, Salvadora persica, Sonneratia caseolaris and Clerodendrum inerme), seaweeds (Acanthophora muscoides and Microdictyon pseudohapteron, seagrasses (Halophila ovalis and Syringodium isoetifolium and lichens (Umbilicaria arpina) were tested for larvicidal activity using Artemia salina nauplii. The LC50 values for the PE-fraction of M. pseudohapteron and A. muscoides and C-fraction of S. isoetifolium were found to be 11.75, 42.5 and 41.5 ppm respectively. Varying LC50 values below 100 ppm were shown by the C-fraction of U. aprine (53 ppm), M. pseudohapteron (72 ppm), S. casseolaris (77 ppm), S. persica (84.37 ppm) and C. inerme (98 ppm). All the remaining fractions were effective at levels between 100 and 500 ppm. The PE-fraction of S. isoetifolium was ineffective even at 500 ppm