Trials of Dipel, a preparation of Bacillus thuringiensis and chitinase, were conducted against larvae of poplar defoliator, Ichthyura anastomosis Steph. in the laboratory. In the first trial there was 100% mortality of larvae within three days of release on poplar shoots treated with 1% and 1.5% concentrations of Dipel and within two days in case of 2% concentration of Dipel. In check there was only 36% natural mortality of larvae. In the second trial there was 100% mortality of larvae within 6 days of release on poplar leaves treated with 0.1%concentration of Dipel and within four days of release on poplar leaves treated with 0.5% and 1% concentrations of Dipel while in check only 30% mortality of larvae in the laboratory condition.