Bioactivity of n-hexane, diethyl ether, ethyl acetate, and n-butanol extract of Piper methysticum was studied to investigate antifeedant and insecticide activity, and interference of the growth of larvae Plutella xylostella L. The nhexane, diethyl ether, ethyl acetate, and butanol extract taken from the leaves of P. methysticum were prepared and tested via the method of selected feed and non-selected feed for test on antifeedant, insecticide, and growth inhibitor of larvae P. xylostella from instar II to imago. The result seemed to reveal that the P. Methysticum leaf extract negatively affected the mortality, antifeedant, and growth and development inhibitor in larvae P. Xylostella. nbutanol extract of P. methysticum has a high mortality level 80% with LC50 378.64 ppm (very toxic), and it can also lengthen the life phase of larvae up to 13.03 days, reduce the probability of formed pupa up to 13.33%, increase the probability of flaw pupa up to 63.33% and 5% for imagoes, and interfere strong antifeeding activity as much as 90.83% and weight inhibition of the larva as much as 95.23%.