Laboratory bioassays were conducted to assess the insecticidal efficacy of the formulated fungi, Beauveria bassiana used alone or in combination with a formulated diatomaceous earth (DE) against adults of Rhyzopertha dominica on wheat grains. Mortality increased with increasing powder concentrations and DE was more effective than B. bassiana. Exposure of R. dominica adults to wheat grains treated with mixtures of B. bassiana and DE resulted in higher mortality values than each powder alone at various concentrations. When eggs were treated with LC₅₀ of each powder alone a significant decrease in adult emergence was achieved. The LC₉₅of the two powders caused complete inhibition of adult emergence. The mixture of the two powders caused complete inhibition in adults emergence except in case of LC₂₅ mixtures which caused about 80% reduction in progeny production. In most cases, B. bassiana and DE treatments did not affect germination of wheat grains as indicated by germination tests.