By extraction and precipitation from several solvents the toxic principle present inAnnona reticulataandA. squamosaseeds and roots has been concentrated up to one hundred‐fold. A preliminary chemical examination of this concentrate is described, leading to the conclusion that the toxicity is due to a glyceride or glycerides of a hydroxylated unsaturated acid or acids of high molecular weight.These extracts have been examined for contact and stomach poison and ovicidal properties in a variety of media. When used as a contact insecticide againstAphis fabae, Macrosiphoniella sanborniandMacronphum solanifolii, the concentrate exhibited a toxicity of the same order as that of rotenone, but againstOryzaephilus surinamensisthe toxicity was considerably less. As a stomach poison the ether extract was both toxic and repellent toPlutella maculipennislarvae, but was neither toxic nor repellent toDiataraxia oleracealarvae. Ovicidal tests against the eggs ofPlutella maculipennisand ofEphestia kühniellawere inconclusive. The potency of this concentrate is therefore of a limited nature and although of roughly the same order as that of rotenone to certain aphides, it has neither the intensity of effect nor the range of insecticidal action of that compou