The toxicity of oil extracts of five medicinal plants was evaluated against the woolly apple aphid, Eriosoma lanigerum (Homoptera: Aphididae). Oils were extracted from Achillea santolina, Artemisia seiberi, Salvia officinalis, Thymus Vulgaris and Senecio vernalis. Each oil extract was used at three concentrations, 100, 1000 and 10,000 ppm. Mortalities were corrected using Abbott's formula and TableCurve fitting program (Jandel Scientific ® ) was used to predict the LC 50 and LT 50 of each oil

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... tract. Results revealed that LC 50 after 24 hr post treatment is 7070, 6161, 6667, 19090 and 9034 ppm for A. santolina, A. seiberi, S. officinalis, T. Vulgaris and S. vernalis, respectively. As time response, LT 50 is obtained at <1, <1, <1, 37 and 14 hr of using A. santolina, A. seiberi, S. officinalis, T. Vulgaris and S. vernalis oils, respectively at a concentration of 10, 000 ppm. At 1000 ppm, LT 50 is obtained at 66, 61, 62,75 and 71 hr post treatment of A. santolina, A. seiberi, S. officinalis, T. Vulgaris and S. vernalis oils, respectively. LT 50 is achieved at 73, 78, 75, 98 and 95 hr post treatment of 100 ppm of oil extracts of A. santolina, A. seiberi, S. officinalis, T. Vulgaris and S. vernalis, respectively. Finally, A. seiberi oil extract was the most toxic to woolly apple aphid in terms of dose and time responses compared with other tested oil extracts, but it was not as toxic as the imidacloprid insecticide that was used at recommended field rate of application (0.25 mL L -1 ). Nevertheless, oil extracts of A. seiberi and S. officinalis provide valuable mortality rates for the woolly apple aphid and can be used as botanical insecticides as part of the integrated pest management programs of this insect pest.