This study was conducted to determine the suitable time to apply the Bacillus thuringiensis sub species kurstaki against the larvae of the Metisa plana oil palm. The aim of this study is to search for the most economical method for using the B. thuringiensis sub species kurstaki. Owing to that matter, the larvae was sprayed at three different times, 0800, 1200, and1600, with 0.68ml of the B. thuringiensis sub species kurstaki product Dipel ES®/200 ml of water, under fully netted, rain sheltered conditions. Results showed the effectiveness of the B. thuringiensis sub species kurstaki in the control of bagworm, with more than 90% larvae mortality in three days after treatment. However there are no significant different in mortality rate and duration killing time for M. plana larvae on these three application times.