Cotton bollworm, Helicoverpa armigera is a major pest in cotton and one of the most polyphagous and cosmopolitan pest species of several crops such as cotton, pulses and vegetables in Asia. Lethal effects of Biolep®, Permethrin and Hexaflumuron belong to three different groups of insecticides were compared on larval stages of H. armigera. The trial was laid out in Randomized Complete Block Design (RCBD) with four treatments including a control and replicated thrice. Our results shown three insecticides, Biolep®, Permethrin and Hexaflumuron had significant difference in larval population mortality of H. armigera. After 3rd day Biolep® caused maximum mortality that was 39 larvae. Permethrin and Hexaflumuron caused 29 and 31 larval mortality after 3rd day, respectively. Generally, the number of mortality decreased and the maximum rate of mortality in 12th day was 7 larvae that obtained by using Hexaflumuron. Our results showed that the Hexaflumuron was persistent in comparison with other insecticides. Biolep® registered above 75% (average 77) reduction in number of larvae on the basis of post-spray data, followed by 68% and 70% each by Permethrin and Hexaflumuron, respectively.