Abstract: The insecticide Chlorfenapyr that inhibits Adenosine Tri Phosphate (ATP) production in cellular structure of insects was first registered in the USA for control of termites, cockroaches and ants under the trade name Phantom. In the present work Chlorfenapyr 5% SL (INTREPIDTM) was used to observe the effect on the Tribolium castaneum development, as well as growth. The sub-lethal concentrations of Chlorfenapyr were given to first instar larvae of Tribolium castaneum through diet of wheat flour for 24 hours. There was effect on development and growth of Tribolium castaneum life cycle by dose dependent manner. There was reduction in larval weight, % pupation and time taken for pupation. Similarly there was reduction % adult emergence and time taken for adult emergence. Adult reproductive potential, fecundity and egg hatchability was also affected. The adult emerged from LC20 concentration laid 76% non-viable eggs and the larvae which were emerged from viable eggs survived for 9 to10 days. The adult emerged from LC40 concentration laid 87% non viable eggs and the larvae which were emerged from viable eggs survived for 6-7 days.