Bactospeine, a commercial preparation of Bacillus thuringiensis was tried against Peismopoda obliquifasciella (Hamps), a serious leaf stitcher of Amaltas, Cassia fistula. The microbial insecticide gave 84.4, 78.1 and 90.7% mortality of the test larvae with dose of 0.8 x 105, 1.6 x105, and 3.2x105 spores per ml against a natural mortality of 34.4% larvae in the check. The efficacy of the product has been proved against this insect hence it can be used on field scale to control the peat.