A dry powder formulation comprising spores of an entomopathogenic fungus that has activity against arthropods that infest dry commodity storage areas, wherein the spores are present in an amount of 2 to 5% w/w of the formulation; particles of an industrial mineral in an amount of 80 to 88% w/w of the formulation and having a volume mean diameter of ≥5 μm; and electret particles in an amount of 10 to 15% w/w of the formulation, and uses thereof.