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Rosemary leaves are characterized by two main periods of essential oils production and contain high levels of oils (2.11 to 3.13%). Their oils, extracted by hydrodistillation and analyzed by GC-FID and GC-MS, are dominated by oxygenated and hydrocarbons monoterpens and contain high amounts of 1,8-cineole. The chemical composition didn’t vary drastically during the phenologic stages, but a noticeable variability is however found within the ten studied populations. PCA and regression analysis revealed that among factors regulating the biosynthesis of oils during the different growth stages of the plant, the mean monthly temperature and monthly precipitation would be determinant. In hives bioassays, the use of absorbent paper pad impregnated by pure rosemary oil for six days showed certain effectiveness against Varroa mites. So, an application rate of 5ml of rosemary oil caused the highest mites mortalities, but the concentration of 3ml that producing an equivalent toxicity to flumetrin, is recommended. To overcome the phenomenon of resistance to chemicals widely used in apiaries infested by Varroa destructor, the use of pure rosemary oils as biopesticide for controlling acarian pests would be an appreciated tool.