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• Croton essential oils blend shows larvicidal effect on Aedes aegypti. • Croton essential oils blend has adulticidal effect on Aedes aegypti. • In mammals the blend administered orally was non-toxic. • Camphor, iso-pinocampheol and (E) caryophyllene are the main compounds of the blend. • The blend has characteristics relevant to the formulation of botanical insecticides. New control alternatives to chemical insecticides, such as botanical essential oils, are important to reduce the population of mosquito vectors. In addition, the use of these oils as insecticides should be safe for mammals. The objective of this study was therefore to evaluate the insecticidal activity of a blend of essential oils from the leaves of Croton argyrophyllus Kunth. and Croton tetradenius Baill. on Aedes aegypti Linnaeus, 1762, as well as to evaluate its acute toxicity in Mus musculus Linnaeus, 1758, and to analyze the chemical composition of this blend. The blend was prepared from a combination of these essential oils in the proportion of 1:1 (m/m). Larvae and adults of Ae. aegypti were used for insecticidal evaluation. In the acute toxicity analysis, the essential oil blend was administered intraperitoneally and orally to M. musculus. Gas chromatography together with mass spectrometry was used for chemical evaluation. The blend presented insecticidal properties, with an additive effect on larvicidal activity (LC 50 =0.16 mg mL-1) and a synergistic effect on adulticidal activity (LC 50 =0.75 mg mL-1). When administered intraperitoneally to mice, the blend displayed intermediate acute toxicity (LD 50 =500 mg kg-1), and no toxicity was observed after oral administration (LD 50 =2500 mg kg-1). Camphor (15.9%), isopinocampheol (12.1%), and (E)-caryophyllene (9.5%) were the main components of this blend. Thus, the blend of essential oils of C. argyrophyllus and C. tetradenius has insecticidal properties against Ae. aegypti and is also safe for mammals, relevant characteristics for the formulation of botanical insecticides. [ABSTRACT FROM AUTHOR]