This work reports the use of Melia azedarach L extracts obtained from supercritical carbon dioxide extraction (SC-CO2) as an insecticidal agent against fall armyworm (Spodoptera frugiperda). For this purpose, SC-CO2 extractions were performed, varying the pressure (150-250 bar), temperature (313-333 K), sample particle size and extraction time. Secondary metabolites from the classes of coumarins, sterols and terpenes were identified in the extracts, with the triterpene melianone being the major constituent. For the biological activity tests, diets were prepared with different SC-CO2 extract concentrations (100, 500, 1000 and 5000 mg/kg) and offered to S. frugiperda (Lepidoptera: Noctuidae). The results indicated that mortality increased with increasing extract concentrations with 50% mortality (LC50) at a concentration of 376.74 mg/kg and reaching 100% mortality at 5000 mg/kg. The inhibition of insect growth was observed at higher concentrations due to the antifeedant action of the extract. At the lowest extract concentration (100 mg/kg), ingestion caused low pupal viability and adults presenting morphological deformities, which thus indicated a chronic toxicity effect. (C) 2014 Elsevier B.V. All rights reserved.