Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), a defoliator of Ulmus species currently present in several regions of central Chile, causes severe damage to trees, mainly in park areas, street tree-lines and gardens. The antifeeding and insecticidal activities of extracts from immature fruit of Melia azedarach L. (Meliaceae) were determined on adults of X. luteola in laboratory bioassays. Several concentrations of the extracts obtained with water and ethanol were used and their effectiveness and LC50 were determined. The antifeeding action of the water extracts caused 100% deterrence over concentrations of 3.6% w/v. Both extracts were effective insecticides against adults, causing 86% mortality (2.4% w/v), with a better performance of the ethanol extracts, with a LC50 of 0.9% w/v on the 3rd day after exposure, and 6.6% w/v on the 5th day with the water extract.