A field experiment was conducted to determine the efficacy of nine chemical insecticides against spotted pod borer, [Maruca vitrata (Fabricius)] infesting blackgram during kharif season of 2008. The results revealed that spinosad 0.009 %, indoxacarb 0.008 %, profenophos 0.05 % and lambda cyhalothrin 0.005 % were found the most effective in reducing the larval population of M. vitrata and also to reduce the pod damage of blackgram. The maximum per cent increase in seed yield (79.37 per cent) of blackgram over control was recorded in the treatment of spinosad 0.009 %. The next effective treatments were indoxacarb 0.008 %, profenophos 0.05 % and lambda cyhalothrin 0.005 %. The treatments of profenophos 0.05 % and lambda cyhalothrin 0.005 % gave the highest incremental cost benefit ratio of 1:12.53 and 1:12.29, respectively followed by endosulfan 0.07 % (1:7.81), profenophos 40 EC + cypermethrin 4 EC (0.044 %; 1:6.81), indoxacarb 0.008 % (1:5.94) and spinosad 0.009 % (1:5.24). Thus, two sprays of profenophos 0.05 % or lambda cyhalothrin 0.05 % or endosulfan 0.07 % or profenophos 40 EC + cypermethrin 4 EC (0.044 %) or indoxacarb 0.008 % or spinosad 0.009 %, first at the time of 50 % flowering and second at 15 days after first spray can be suggested to the farmers for controlling this pest on blackgram and to get more benefit during the kharif season.