Laboratory experiments were carried out to study the effect of different citrus varieties as host plants on the biological aspects of the Seychelles fluted scale Icerya seychellarum. The experiments were carried out in the insectary of the Economic Entomology Department, Faculty of Agriculture, Mansoura University under Fluctuated temperature degree of 22.4±3.1^ºc and R.H. 60±5 %. Results represented that, the total developmental period was the shortest when I. seychellarum reared on common balady orange which represented by 48.7±1.3 days. The survival rates during the nymphal stage of I. seychellarum were the highest on common balady orange, followed by Lemon, Navel orange and  the lowest observed on Succari (sweet) orange and Mandarin. According to the previous results the index of suitability of different citrus host plants arranged in descending are as follows : on common balady orange, Lemon, Navel orange, Succari (sweet) orange and Mandarin. The oviposition period, adult longevity and the fecundity was the highest when the adult females were reared on common balady orange (23.5±1.1, 59.4±2.3 days and 56.2±4.1 eggs/female), respectively.