Thesaponins are glycosides with wide distribution among plants which may be to xic for herbivorous arthropods. Their insecticidal activ ity may be associated to the ability of producing alterat ions in the feeding behavior, in the mo lting process and causing death. This study evaluated the lethal and sub lethal effects of a saponins extract, obtained fro m Passifloraalata on Spodopterafrugiperda, by ingestion tests with artificial diet. Nine solutions with increasingextract concentration and a control solution with sterile distilled water were used in the test. In total 1500 insects were used in 5 repetitions, 30 replicates per concentration. Considering the total mo rtality, all treat ments differed statistically fro m the control one, but not among them. Most of the observed effects were sub lethal, in which 68.3% insects presented deformation. The nu mber of deformed insects per treatment increased as the extract o f saponins concentration increased. In conclusion the mortality revealed significant difference between control and other treat ments, which indicated the potential of saponins present in P. alata as a control agent of S. frugiperda. This potential needs to be better evaluated, especially if the facilities of raising and large scale production of the plant are considered.