Insects use a variety of proteases for the digestion of their food proteins. In this study we identified the major type of protease present in the larval gut extract of Spodoptera mauritia, a major pest of paddy, using commercially available protease inhibitors. We found that Phenyl Methane Sulphonyl Fluride (5mM) and Benzamidine Hydrochloride (10 mM) inhibited larval gut proteases to the extent of 72.39±1.37% and 39.41±2.04% respectively. N-Ethyl Maleimide, a cysteine protease inhibitor, inhibited the gut protease activity up to10.80±0.33% and Pepstatin, an aspartyl protease inhibitor, inhibited the gut protease activity up to 2.67±0.22% only. Thus it is clear that the predominant protease present in the larval gut of S. mauritia is serine proteases. On SDS-PAGE three major and two minor protein bands were identified in the gut extract of S. mauritia. Further characterization of the major gut proteases of S. mauritia will be helpful in targeting the gut proteases for the control of the pest.