Amaltas, Cassia fistula a beautiful ornamental and avenue tree, well known for its medicinal value and producing a very valuable timber is severely attacked by a leaf stitcher, Piesmopoda obliquifasciella (Hmps). Heavy infestation tarnish the beautiful look of the tree for which it is grown as well as destroy annual growth of the tree to the extent of 50-100% depending upon severity of infestation. For developing a control method safer to the environment a pathogenic fungus, Beauveria bassiana (Bals.) Vuill. Was tried against the larval stages of the pest. The fungus displayed its pathogenecity by killing 72.5-97.5% larvae in various treatments as against 50% natural mortality in check treatment. The method can safely be used against the pest on larges scale.