The biology and predatory potential of Coccinella septempunctata and C. transversalis feeding on Lipaphis erysimiin the mustard ecosystem has been studied. The biology of C. transversalis showed that egg, larval, pupal, adult male and female periods were 2.70± 0.766, 12.68± 1.633, 2.62± 0.696, 30.12± 4.492 and 33.88± 2.566, respectively while that of C. septempunctata were 4.40± 0.77, 13.67± 1.77, 6.73± 1.11, 31.33± 3.28 and 37.30± 3.44, respectively. The fecundity and hatching % of C. transversalis and C. septempunctata were 364.88± 27.446, 582.44± 93.15 egg/female and 84.73± 8.114, 73.3± 5.27 %, respectively. The predatory potential when observed the result reveal that consumption by different instars i.e., 1 st , 2 nd , 3 rd and 4 th instar of C. septempunctata were 15.86± 0.34, 45.1± 0.45, 124.62± 0.88 and 238.82± 1.11 aphids, respectively, whereas 1st , 2 nd ,3 rd and 4 th instar of C. transversalis consumed 19.95+3.23, 34.25+4.36, 58.30+7.54 and 65.67+8.23 aphids, respectively.