Worldwide, wastewaters constitute a major environmental pollutant. They are very toxic against a wide range of plants and soil microorganisms. Their toxicity is due to the presence of compounds such as polyphenols. In this study, we have isolated yeast strains from the endogenous microflora of the olive flies Bactrocera oleae larvae that were capable of degrading the olive oil mill wastewater polyphenols. The results obtained showed the presence, in the digestive tract of the larvae, of yeast strains resisting to polyphenols. Two resistant strains were isolated and have shown variable capacity of polyphenols degradation that could reach up to 72%. The two isolated strains were identified by two methods: conventional technique and molecular method associating PCR amplification and DNA sequencing of the 5.8S ribosomal RNA gene. Both techniques showed that the two isolated strains corresponded to the Candida diddensiae specie. Related to its capacity to degrade polyphenols, this specie would be a potential candidate for wastewater treatment and environmental protection.