The present investigation on Bioefficacy of combination insecticides against major insect pests of Bt cotton under high density planting system carried out to evaluate safety combination insecticides against beneficial insects of Bt cotton under high density planting system. The results indicated that all the insecticidal treatments were found to be significantly superior in recording minimum number of sucking pests and bollworms over untreated control.

Among all insecticides thiamethoxam 12. 6% + lamdacyhalothrin 9.

5% ZC, indoxacarb 14. 5% + acetamiprid 7.

7% SC and acephate 50% + imidachloprid 1. 8% SP were found to be effective in reducing aphid, jassid, and whitefly population.

The insecticides thiamethoxam 12. 6% + lamdacyhalothrin 9.

5% ZC, indoxacarb 14. 5% + acetamiprid 7.

7% SC and acephate 50% + imidachloprid 1. 8% SP were found to be effective against larval population, fruiting bodies, rosette flowers, green boll damage, open boll damage and locule damage due to american and pink bollworm.

The highest population of natural enemies was recorded in the plots treated with thiamethoxam 12. 6% + lamdacyhalothrin 9.

5% ZC after each spray with highest yield and ICBR. .