The present study was aimed at the evaluation of two isolates of Aspergillus flavus and two isolates of Penicilium corylophilum on third stage larvae of Musca domestica. The samples tested were isolated directly from M. domestica specimens. Third stage larvae were obtained from pupas of a laboratory colony. Four batches with 20 larvae were used for each of conidia dilution tested (10(5) to 10(8) conidia/ml). Larvae were dipped for one minute into conidia dilution, being then moved to dishes and kept under controlled environmental conditions. Two control groups were used: one received a treatment with spreading adhesive and the other one with no treatment at all. Larval surviving rates were: 57.50% and 86.25% for groups treated with 10(8) conidia/ml of A. flavus; and 63.75% and 72.50% for those who had received the same concentration of P. corylophilum conidia. Larval mortality rates were greater for groups that received higher conidia concentrations, and also increased directly proportional to exposition time. Adult hatching rates on treated groups, were affected by fungi treatment. It was concluded that A. flavus and P. corylophilum presented detrimental effects for third stage larvae of M. domestica