A field study was conducted to evaluate the efficiency of four microbial insecticides viz. Beauveria bassiana; HaNPV (Helicoverpa armigera Nuclear Polyhedrosis virus); (Bacillus thuringiensisvar.kurstaki 2 gm/L); HaNPV+Bt; neem oil; neem cake and D.D.V.P EC 76% @0.05% at Research Farm SHIATS,Allahabad during rabi season of 2011-2012. The experiment was laid out in randomized block design with seven treatment and replicated thrice. The observation larval populations of H. armigera were recorded one day before treatment was recorded at 3,7, and 10 days after treatments. The larva population of H. armigera appeared in the third week of February (8 the Standard week) and reached its peak of 14.65 larvae in first week of April and decline rapidly with maturation of crop. There was only one peak in the larval population observation in the 1st week. Bacillus thuringiensis was the most effective chemical by D.D.V.P.76%@0.05% . Among the microbial insecticides. HaNPV ,was the most effective followed by HaNPV+Bt and neem cake . The combination treatments were less effective than the individual treatment neem oil and B. bassiana were the least effective treatment in reducing the larval population of Heliverpa armigera.