Calliphoridae (Blowflies) are a dangerous group of mechanical vectors of many microbes. The present work was carried out to study the prevalence and diversity of adult Calliphoridae flies and to isolate and identify bacterial strains from their external surface. A total of 558 Calliphoridae adult flies belonging to subfamily (Chrysomyinae, Luciliinae), two genera (Chrysomya, Lucilia) and six species (Lucilia sericata, Chrysomya albiceps, Ch. marginalis, Ch. putoria, Ch. megacephala, Ch. Bezziana) were collected from Hihya in middle Al-Sharqia Governorate, Egypt through the study time from April 2023 to March 2024. The abundance and diversity of subfamily Chrysomyinae (418 individual, 74.91%) were more than subfamily Luciliinae (140 individual, 25.09%). Temperature and humidity had a major role in the density of flies during the study period. The type of bait (fish or liver or meat) to attract adult insects had an impact on their density and diversity. There was also evidence of a single-year variance regarding files distribution and abundance of bacterial isolates between seasons, which could be attributed to weather. After isolation and identification fifth species were discovered as following, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Salmonella typhimurium. The incidence of the microbial species did not show any significant change throughout different seasons however, it was appeared to be significantly varied according to the type of flies.