Severe outbreak of the army worm, Mythimna separata (upto 35 larvae/ plant) during the rainy season of 1988 in the transition tract of Karnataka was contained by the use of poison bait. Application of poison bait containing monocrotophos (mixture of 250 ml monocrotophos 36 EC + 50 kg rice or wheat bran + one kg jaggery + 6 to 8 litres of water) was superior giving 98 per cent mortality compared to spray with monocrotophos (97.83% mortality), endosulfan (73.6% mortality), chlorophyriphos (75.43%) mortality), decamethrin (73.20%) or whorl and leaf axil application of BHC dust (64.33% mortality) and carbofuran (86.53% mortality) in suppressing the population. Monocrotophos was phytotoxic. A dose of 25 kg poison bait per ha would manage the pest satisfactiorily under normal situations ( 0 to 5 larvae/plant). The migratory larvae fed voraceously on sorghum, maize, pearl millet, little millet, finger millet and sugarcane and defoliated the plants. Four new host plants have been recorded.