The aphid B.brassicae is a key pest of various cruciferous crops like cabbage, cauliflower, kale and other such Brassica species. The objective of the present work was to evaluate the effect of texture/morphology of two cruciferous crops viz. cauliflower and turnip on the biology of B.brassicae under natural conditions of temperature and humidity. The mean developmental period, reproductive period, adult longevity and total longevity so recorded were subjected to t-test. The developmental period on turnip was recorded as (9.91 days) and on cauliflower as (8.75 days). The reproductive period on cauliflower and turnip was recorded 18.8 and 4.29 days respectively. Similarly the adult longevity on cauliflower was recorded as (20.98 days) and on turnip as (6.17 days). The total longevity on cauliflower and turnip was recorded as 28.92 and14.88 days respectively. The results revealed significant differences in the biological parameters of B.brassicae on cauliflower and turnip. The differences in the biological parameters in cauliflower and turnip can be attributed to differences in nutritional quality, physiology and morphological structure of the host plants.