Insect-proof nets with mesh size higher than 0.5 mm cannot efficiently protect cabbages against aphid infestation and insect-proof nets with very fine mesh reduce the ventilation. The objective of this study was to show the biological efficacy of a polyethylene knitted net with 0.9 mm mesh size impregnated with 1% alphacypermethrin, an excito-repellent insecticide, using the Olyset® process recommended for public health use by WHO. A cabbage crop was used to study the treated net efficacy in a statistical bloc design, compared with non-treated nets (with 0.9 or 0.4 mm mesh size). A non-protected control was included in the experiment. All cabbage pests where observed periodically and particularly the aphids: Lipaphis erysimi, Brevicoryne brassicae and Myzus persicae . In the same time, laboratory tests were used to show the insecticide susceptibility and the behavior of M. persicae stimulated to cross treated and non-treated nets. The major result was total protection of cabbages under the treated net against all aphid species during 10 weeks of monitoring until harvest. In the contrary M. persicae and L. erysimi outbreaks were both observed under non-treated nets. In the laboratory, the treated net did not show a toxic effect on M. Persicae and on the parasitoid Aphidius colemani. The bioassay with dipping leaves showed a highly resistance of M. persicae to alphacypermethrin. Therefore a repellent effect with the treated net was observed against M. persicae and against the parasitoid A. colemani. Thus that repellent treated net could be a solution for protecting vegetables against aphids with a low impact on beneficials. (Texte intégral)