Abstract The need for new bioinsecticidal compounds motivates the study of natural products. Therefore, we studied the activity of Crescentia alata Kuth (Lamiales: Bignoniaceae) against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). We showed that C. alata has bioinsectidal activity. After 7 days of exposure to C. alata fractions in the diet at 200 ppm, fractions 3, 4 and 7 caused 90.7% weight loss in the larvae, and at 100 ppm, fractions 2, 4, 7 and 8 caused 90.1% weight loss with respect to the control. After 14 days of exposure to fractions 4 and 7 at 200, 100, and 50 ppm, the larvae had lost 94% of their weight compared to the control. There were large differences in larval mortalities between treatments, and fractions 5 and 6 at 200, 100, and 50 ppm induced the highest mortalities, which ranged from 65 to 80%. Possibly the iridoids identified from the C. alata fruit fractions are responsible for the antifeedant activity and mortality of S. frugiperda. This is the first report of C. ala...