The study was carried out in the period 2008 – 2009 in the Institute of roses and aromatic plants – Kazanlak. The preparation was used against Macrosiphum rosae L. in a plantation with Rosa damascena Mill. at a dose of 500 ml/ha. Observations were made in the following continuity: preliminary treatment, on the 3rd, 7th and 14th day. The effectiveness of the insecticide “Mido 20 SL” was calculated according to the formula of Henderson and Tilton – in the range between 99.80 – 94.50 % for the period. “Mido 20 SL” is effective against Macrosiphum rosae L., but it has a toxic effect on useful insects in the plantation.