Maskell scale, Insulaspis pallidula (Green) is common scale insect on mango trees, Mangifera indica, resulting falling the leaves and the drying branches. Population dynamics, number and duration of generations and effect of two weather factors on the insect activity were studied at Horticulture Research Station in EI-Qanater EI-Khairia,Qalubia Governorate (25 km north Cairo) in 2001/2002 and 2002/2003 years. Results revealed that, pre-adult and adult populations peaked four times per year during May, July, September/October and November. The pest had four annual overlappmg generations and the highest generation occurred during autumn in both studied years. The daily mean temperature was entirely under the optimum range of pre-adults and adults activities in the two years, whereas, the daily mean relative humidity within the optimum range of the pre-adults and adults activities in 2001/2002 year, and entirely under the optimum range of the pre-adults and adults activities in 2002/2003. The combined effect of the two weather factors on the pre-adults and adults activities was highly significant in both studied years.