Studies were carried out to determine the effect of Cleistanthus collinus L. fruit extracts on the third instar Plutella xylostella using leaf disc bioassay method. Seven different concentrations (1, 3, 5, 7, 9 and 11%) along with untreated control were tested. The extracts showed divers anti insect properties such as insecticidal and insects growth regulatory at different concentrations. Among the hot water and water extracts of leaves, hot water extract showed maximum larval mortality activity of 80%per cent in higher concentration. When concentration increased the larval mortality was also found to be increased.