Aphid population commenced from 4th Week After Sowing (WAS) [1st week of December (49th Standard Meteorological Week- SMW)] with aphid index 0.14 and reached to peak (4.9 aphid index/plant) at 15th week after sowing i.e., 3rd week of February (8th SMW). The correlation matrix indicated that the aphid population had highly significant positive correlation with evaporation (r = 0.627 ) and significant and positive relation with minimum temperature (r = 0.514 ). The avoidable loss in yield of mustard due to mustard aphid, L. erysimi estimated 60.70 per cent. The yield recorded in protected plot was 1559 kg/ha which showed 191.94 % yield increase over control while unprotected plot recorded 825 kg/ha. In nutshell, based yield and economics; imidacloprid 0.005% was found to be the most effective and economical insecticidal treatment followed by dimethoate 0.03%, flonicamide 0.02%, thiamithoxam 12.6% + lambda cyhalothrin 9.50% @ 0.015%. Thus, it can be recommended for the management ofaphid in mustard.