The stored samples of food grains of wheat and rice(60 samples) were purchased from places of Eastern UP and Gurgaon district Haryana. Its moisture contents were estimated.The Mycological investigations of wheat revealed presence of a total number of 16 fungal species viz., Alternaria alternata, Aspergillus candidus ,Aspergillus flavus, A. niger, A. ochraceous ,A. phoenicis, A. tamari,A. terreus, A. sydowi ,Fusarium moniliforme, F. oxysporum F. solani ,P. glabrum ,Rhizopus nigricans, Trichoderma viride and Trichothecium roseum. While Mycological analysis of rice seeds showed presence of 15 fungal species viz., Alternaria padwickii, A. oryzae, Curvularia lunata, Fusarium moniliforme, Aspergillus clavatus, A. flavus, A. niger, Cladosporium sp., Nigrospora oryzae, Alternaria tenuissima, Chaetomium globosum, F. solani, Microascus cirrosus, Helminthosporium oryzae, Pyricularia grisea.It also projected variation in presence of fungal species in blotter and agar plate method of analysis. The insect analysis revealed that wheat samples were infected with Tribolium castaneum.While rice sample showed presence of insect Sitophilus oryzae. The investigations revealed that Aspergillus flavus, A.niger, Sitophilus oryzae and Tribolium castaneum caused reduction in seed weight loss, seed germination,carbohydrate and protein contents of common food grains(wheat,rice).It also revealed that randomly selected A. flavus isolate 1 of wheat showed higher potential of aflatoxin B1 production (1392.940 µg/l) while rice isolate 2 showed 1231.117 µg/l production.