among strategies for decreasing diseases, the use of larvicidal plant extracts against mosquito larvae gain an important place in vector control. the aim of the present study was to reveal the insecticidal effectiveness of an endemic medicinal plant on mosquito-borne diseases. the chemical composition of the dried aerial part from origanum floribundum essential oil, obtained by hydrodistillation, was characterized by fourier-transform infrared (ftir) spectroscopy and gas chromatography-mass spectrometer (gc-ms) system. the potential larvicidal activity of this extract as bioinsecticide was assessed against culex pipiens. results showed many functional groups such as phenols and alcohols, besides, the chemical composition by gc-ms identified thymol (86.9%) and p-cymene (5.1%) as major components. a significant larvicidal effect against the target mosquito species was noted, with values of lc 50 at 21.19 mg/l and lc 90 at 68.37 mg/l. the results obtained showed that the essential oil of origanum floribundum with chemotype thymol possess a potent larvicidal activity and could be considered as an eco-friendly alternative for vector control.