This study assessed the toxicity effects of powder and solvent extracts of the leaf and root bark of Calotropis procera and Parquetina nigrescens on the mortality of Callosobruchus maculatus treated with powder and extracts of the leaf and root bark of the plants. These were with a view to developing a new biological method of control of the insect pest. Different concentrations of the powder and solvent extract leaf and root bark of C. procera and P. nigrescens were used for toxicity test on adults and second instar larvae of C. maculatus. The results showed that second instar larvae of C. maculatus treated with the ethanolic and methanolic extracts of leaf and root bark of C. procera and P. nigrescens at 5% concentration had 100% mortality for various plant extracts except for the extracts of C. procera root bark where mortality ranged between 70 to 85%. The mortality of the adults of C. maculatus was 100% in all the ethanolic and methanolic extracts of leaf and root bark of C. procera and P. nigrescens at 5% concentration.