Theÿred flour beetleÿ(Tribolium castaneum) is a common pest insect known for attacking and infesting stored flour and grain. They are one of the most common and most destructive insect pests for grain and other food products stored in silos, warehouses, grocery stores, and the home. Bacillus thuringiensisÿ(B.t) is a Gram positive, soil dwelling bacteria commonly used as a biological alternative to a pesticide. The present project was designed for the study of combined insecticidal effect of Bacillus thuringiensis along with boric acid, insecticide cypermethrin and the plant leaves powder i.e Azadirachta indica against the Tribolium castaneum to check the mortality rate of these insects and LC50 was calculated. Bacteria were isolated from rich soil, pulse dust, grain dust and its growth was checked on the T3 media by applying the microbial techniques. On the other hand the larvae of T. castaneum were reared in empty glass jars, the third instar larvae and the adults were collected which were used in insecticidal bioassays.