The use of conventional silos for grain storage involves application of synthetic pesticides that produce harmful residue after use. This study was aimed at investigating the efficacy of NSPRIDUST® as a protectant for maize stored in silo with respect to insect control and quality maintenance. Maize treated with NSPRIDUST® in ratio 1:1000 (NSPRIDUST®: Maize) by mass was stored in 2 experimental silos of 500 kg loaded to 80% of its capacity. The NSPRIDUST® was applied to the maize using NSPRIDUST® applicator. Another set of 2 experimental silos were loaded with untreated maize to capacity to create hermetic condition (control). Five hundred (500) newly emerged unsexed adults of Sitophilus zeamais (primary insect pest of stored maize) were introduced into each silo in batches of one hundred (100) insects to ensure proper distribution of the as the grains were loaded. The maize was stored for 12 months and samples were drawn from the silos monthly to determine insect count, germinability and moisture content, while microbial loads and proximate composition were determined before and after the storage using standard laboratory methods. The result shows that the NSPRIDUST® treated maize had no live insect and suppressed F1 generation throughout the storage period depicting a 100% insect mortality, while insect mortality in the control were 75, 83.33 and 100% for the first, second and subsequent sampling months respectively. The effects of NSPRIDUST® on the live insect count, F1 emergence and moisture content of maize grains were statistically significant (p < 0.05). NSPRIDUST® caused reduction in bacteria load and fungal count by 80 and 73% respectively, and both were within the acceptable limit (<0.3 x 103 cfu/g). It is an effective protectant for maize in silo storage as it maintained grain quality and suppressed proliferation of microbial loads during the storage. Therefore, the application of NSPRIDUST® as a grain protectant could be extended to silo storage of grain.