The phytochemical camptothecin (CPT) from Camptotheca acuminate (Nyssaceae) and the byproduct bamboo tar (BT) from bamboo charcoal making are insoluble in water. Here, we prepared water-soluble CPT-Na and BT-Na by alkalization of CPT and BT and a mixture of both salts (CPT/BT-Na), and evaluated their insecticidal activities against brown planthopper Nilaparvata lugens and Asiatic rice striped borer Chilo suppressalis under laboratory and field conditions. The modeling analysis of time-concentration-mortality responses indicated that the lethal concentrations (LC50 and LC90) of CPT-Na and BT-Na sprayed together against the two rice pests were reduced, respectively, by 3.5-14.8-fold and 3.3-29.1-fold in comparison with the estimates of the two salts sprayed separately. The reduction magnitude varied with post-spray days. These highlight a strong synergism of the two salts in insecticidal activity. In two field trials, a spray of CPT/BT-Na (CPT-Na + BT-Na: 1.5-3.0 + 135-270 g ha(-1)) resulted in more efficacious and persistent rice pest controls than not only a doubled spray of either CPT-Na or BT-Na, but also a recommended spray of imidacloprid against N. lugens or fipronil against C. suppressalis. All together, the mixture is a promising botanical insecticide for effective management of different rice insect pests.