The tortoise beetle, Cassida vittata Vill. (Coleoprera: Chrysomelidae) is a serious pest on sugar beet, Beta vulgaris L., in Egypt. Four free pesticides's fields were planted with Raspoly sugar beet variety to study some aspects of ecology and egg parasitism of this pest at Bilqas and Shirbin in Dakahlia governorate during 2004- 2005 and 2005- 2006 growing seasons. Obtained results proved that level and intensity of infestation, population density of larvae, pupae and adults and no. of deposited and parasitized eggs were fluctuated greatly. It ranged between about 64-73%, 7- 9 feeding pores/4 cm2 leaf disc, 6-9 individuals/leaf,12-16 eggs/leaf, and 19- 29% at Bilqas and Shirbin, respectively. In both regions, the general means were about 70% infestation rate, 7 feeding pores/4 cm2 leaf disc, 8 individuals or 17 eggs/leaf and 21% parasitized eggs in 2004- 05 opposed to 67% infestation rate, 8 feeding pores, 8 individuals or 11eggs/leaf and 26% parasitized eggs in 2005- 06, with general means about 68% infestation rate, 8 feeding pores, 8 individuals or14 eggs/leaf and 24% parasitized eggs. Feeding pores increased by increasing population density of larvae and adults reached its peak in early June. Ovipositional activity by C. vittata females as well as parasitic activity by the egg parasitoid Monorthochaeta nigra (Hymenoptera: Trichogrammitdae) started in mid March and continued until early June in both seasons. Deposited eggs peaked earlier and two weeks later than parasitized one in the first and the second seasons, respectively.