In this research, we evaluated the aphicidal effect of the ethanolic extract of stems and bark of Ficus petiolaris Kunth (Moraceae), in laboratory bioassays in an artificial diet against apterous adult females of Melanaphis sacchari Zehntner (Hemiptera: Aphididae). The extract was evaluated at different concentrations (500, 1,000, 1,500, 2,000, and 2,500 ppm), and the highest percentage of mortality (82%) was found at 2,500 ppm after 72 h. The positive control imidacloprid (Confial®) at 1% eliminated 100% of the aphids, and the negative control (artificial diet) only presented mortality of 4%. The chemical fractionation of the stem and bark extract of F. petiolaris yielded five fractions of FpR1-5, which were each evaluated at 250, 500, 750, and 1,000 ppm. FpR2 had the strongest aphicidal effect, with 89% mortality at 72 h at 1,000 ppm. The pure xanthotoxin compound extracted from this fraction was even more effective, with 91% aphid mortality after 72 h at 100 ppm. The lethal concentration (LC50) of xanthotoxin was 58.7 ppm (72 h). Our results indicate that the extract of F. petiolaris showed toxic activity against this aphid, and its xanthotoxin compound showed strong aphicidal activity at low concentrations.