White mango scale, Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) is a serious pest on mango (Mangifera spp.), (Sapindales: Anacardiaceae) which became recently a trouble some pest in all mango orchards in Egypt. Biology of the scale insect A tubercularis (Hemiptera: Diaspididae) was studied on mango saplings (Mangifera sp.)   at mean temperature of 30°C and relative humidity (RH) of 64 % at the laboratory during summer and winter seasons in Department of Agriculture Ain shams university, Government of Qalyubiya, Egypt. Observations of developmental stages and morphometry of A. tubercularis were conducted using a head lens and an ocular and stage micrometers. In the laboratory conditions, mature females laid 85-200 eggs in 10–12 days under the scale cover; the eggs hatched after 6–7 days. A. tubercularis males passed through two feeding instars then pre-pupal, pupal and adult stages while females had two immature instars with pre-oviposition, oviposition and post-oviposition periods. Mean developmental span (egg to adult) of male insect was 53.5 days and for female was 67 days. The periods of the age and survival stages were almost close to the point of congruence in some stages. Mean developmental periods on mango saplings in summer were 8, 32, 2, 4, and 2 days for stages of males and 8, 32, 10, 12 and 8 days for stages of females, respectively while in winter were 8, 30, 2, 4, and 3 days for stages of males and 8, 30, 8, 12 and 12 days for stages of females, respectively.