In the current research, the insect pathogenic fungus, Is aria fumosorosea was assessed for its pathogenecity against adults of different aphid species of wheat and Brassica crop i.e. Schizaphis graminum, Rhopalosiphum padi, Brevicoryne brassicae and Lipaphis erysimi. I. fumosorosea (IF-01) was found effective at all concentrations i.e. 1x106, 1x107 and 1x108 spores/ml on all aphid species, but the uppermost concentration (lx108 spores/ml) provided maximum control within short period of time (P < 0.05). The results showed that the effect of I. fumosorosea on different aphid species was dose and time dependent. I. fumosorosea with LC50 value of 9.02 x 105 proved to be lethal to L. erysimi after 3rd day. Mortality of B. brassicae was observed maximum on highest concentration of 1x108 spores/ml with LC50 value of 1.64 x 107 , while the LT50 values were in range of 1.78-4.53 days for different aphid species treated at various concentrations. By checking the field efficacy of I. fumosorosea against aphid species, this entomopathogenic fungus can be used as possible biological control agent for suppressing aphids.