The green vegetable Brassica oleracea var.Botrytis.is one of the most delicious food item for the common people. It is cosmopolitan in distribution and the farmers cultivate it as cash crop throughout the year. Brassica oleracea var. Botrytis. The cauliflower is commonly called as fulgobhi. Brassica oleracea var. botrytis is a delicious as well as nutritive vegetable .It is rich in potassium, sodium, calcium, vitamin B6, very low quantity of fat, and carbohydrate. Cholesterol is totally absent, very low calories recommends it as a healthy food for the people. The farmers of Ramgarh produces abundant quantity of cauliflower and supply it to the metro cities through road and rail .It is one of the main crop to get sound earning. The vegetable pest Pieris brassicae Linnaeus, is a serious pest damage the vegetables of cruciferous plant. The larvae of this pest damage the crop at every stages. The younger stage larva just scrapes the surface of the leaves and later they enter in the flower eaten voraciously and result the destruction of the host plant and the flower remain with full of excreta .The infestation is so serious that sometimes all the crop of the field destructed by the pest. The younger stage larvae eat the soft leaves and damage the foliage, later the larvae eat the flower, the complete flower was damage and the excreta of the larvae remain there. The larvae is the only destructive stage. The pest not damage the crop only but it decline the nutritive value, the taste, it also damage the marketing of the crop. The life cycle was studied during the year 2018 -2020 at Ramgarh. During the study It was found that the life-history of pest was very simple generally it completed 04 to 05overlapping generations between September to May of a year .The pest damage the cultivated vegetable plants and loss not only the quality, quantity, and taste of the vegetables but also the profit of the farmers. Ramgarh is a beautiful district town, the rural area is known for agriculture and gross vegetable production, the climatic condition is moderate and suitable for the cultivation of Brassica oleracea var. botrytis vegetable. The experimental pest destroy the cultivated plant. The farmers are advised to control the pest by chemical pesticide spraying carbary l 0.2%, malathion 0.05%., or diazinon 0.02%.