AbstractThe virulence of five fungal strains, Acremonium cephalosporium, Aspergillus niger, Penicillium chrysogenum, Trichoderma viride, and Verticillum albo-atrum by application of 108 conidia mL−1 to larvae and adults of house flies, Musca domestica was determined. A. niger produced the highest percentage of mortality to larvae, 85.1 ± 1.60, and adults, 98.2 ± 3.10, of house flies. Topical application of the fungal strains to larvae showed concentration-dependent response and caused mortality ranged between 41% and 83% with LT50 values varying between 5.22 and 7.81 days. The highest percentage of mortality, 83.9 ± 3.52, was produced by 107 conidia mL−1 of A. niger with LT50 5.22. The lowest mortality percentage, 41.2 ± 3.00 with LT50 7.81, was produced by 105 conidia mL−1 of V. alboatrum. On the other hand, the highest percentage of mortality to adults of house flies, 97.3 ± 3.52, was produced by 107 conidia mL−1 of A. niger with LT50 3.49. While the lowest mortality percentage, 59.1 ± 2.38 with LT50 6.91, was produced by 105 conidia mL−1 of V. albo-atrum.