Green marine algae (Codium sp.) was extracted sequentially with different organic solvents on cold. Lima bean leaf discs treated with the different extracts were offered to adult female T. urticae for 96 hr and the corrected percentage mortality of the females was calculated. The toxicity of the different extracts to the eggs was also recorded. Petroleum ether extract of this seaweed was highly toxic to females at 4 g/ml. At 1 g/ml ca. 48% of the individuals were killed. Chloroform and ethyl alcohol extracts were found to be poorly effective against the females even at high concentrations (4 g/ml) where less than 50% of the individuals died after 96 hr. Toxicity of crude extracts to the egg stage was less pronounced and chloroform extract was found to be more efficient than the other extracts tested.