Botanical pesticides are an alternative of synthetic chemical pesticides for pest control in modern ecological technologies. These products are not a threat for the environment and human health. Plant products have a number of advantages that make them preferable in modern organic agriculture. The range of these products is constantly expanding, which requires the mechanism of their action to be well known. During the period 2013-2014 a number of studies were conducted for establishment of the effectiveness of plant oils from mustard (Sinapis alba L.), hemp (Cannabis sativa L.) and yarrow (Achillea millefolium L.) in concentration 0.5% and 1% against the cotton aphid (Aphis gossypii Glov.) in cucumber variety Kiara F1, grown in greenhouses. Chemical product Mospilan 20 SP 0.0125% (a. i. acetamiprid) was included as a standard. The 1% plant oils from hemp and yarrow demonstrate a good effectiveness (over 90%) to cotton aphid. The highest values of biological activity of the plant oils, included in the study were observed at 5th-7th day after treatment. The good effectiveness shown by the plant oils, gives us another alternative to control this pest in greenhouse cucumbers