Triacontanol Hormone (TRIA)was evaluated against Myzus persicae (Sulzer) infesting carnation flowers (Dianthus caryophyllus L.)under plastic greenhouse conditions during season 2024. Experiments took place at two different Governorates; Cairo (El-Zohrya Garden) and Alexandria (El-Horya Farm), three different concentrations were used; 25ppm,50ppm and75ppm.Results indicated that carnation plants treated by25 ppm of (TRIA) hormone were less infested comparing to control, while treatment by 50ppm had non-significant effect on infestation. Whereas plants treated by 75ppm were more infested. Further results indicated that individuals fed on carnation plants treated by 25ppm showed bad effects on the physiological vital processes especially on some important internal substances secreted by the insect as ; (carbohydrates, total lipids, total proteins and important enzymes such as; Lipase enzyme , Phosphatase enzyme ,Chitinase enzyme, , Kinase enzyme, Beta esterase enzyme, Alpha esterase enzyme, Digestive enzymes ,and Oxidation enzymes). Insects fed on plants treated by 50 ppm had non-significant effect on the internal secretions of the insect, lastly individuals fed on plants treated by75 ppm showed enhanced internal substances secreted by insects.