Derris elliptica Benth extracts containing rotenone have long been used as natural insecticides, but time-consuming preparation processes and the short shelf life of the extract limit their use in pest control. In this study, stable water-dispersible granules and emulsifiable concentrate liquids containing Denis extract (equivalent to 5% w/w of rotenone) were developed with simple techniques. Accelerated degradation kinetics of rotenone in the Derris extract, and in both formulations, indicated that its degradation followed first-order kinetics. The predicted half-life (t1/2) and shelf life (t 90%) at 30 °C of rotenone in Derris extract were 520 and 79 days, respectively. Derris granules and emulsifiable concentrate clearly prolong the stability of rotenone 8-fold (t90% = 633 days) and 14-fold ( t% = 110 days), respectively. The study of rotenone degradation after application onto plants Indicated that both formulations would be effective for up to 3 days after spraying. Preliminary efficacy testing indicated that the Derris emulsifiable concentrate was clearly more effective than Denis water-dispersible granules in controlling Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). ©2009 American Chemical Society.