This study was carried out to study the effect of treated strawberry plants, Fragaria ananassa (L.) by Triacontanol Hormone (TRIA) "three concentrations" on the infestation by Myzus persicae (Sulzer) under glasshouse conditions. Experiments were done in two locations (Governorates), Nobariya (Behera Governorate) and Perkash (Giza Governorate) during season 2019/2020. Three treatments (concentrations) of Triacontanol Hormone were done in both two locations, small concentration (35ppm), medium concentration (50ppm) and high concentration (65ppm), besides the fourth treatment which did not treat with any hormone (control).
           Strawberry plants were treated with small concentration of (TRIA) (35ppm) were lower infestation by M. persicae comparing to control. While strawberry plants which treated with medium concentration of (TRIA) (50ppm) had no clear effect on the infestation by M. persicae comparing to control. On the other hand, strawberry plants which treated with high concentration of (TRIA) (65ppm) were higher infestation by the same insect comparing to control.