The potential for contributions of entomology to legal investigations has been known for at least 700 years, but only within the last two decades or so has entomology been defined as a discrete field of forensic science .There are many ways that insects can be used to help in solving a crime, but the primary purpose of forensic entomology is estimating time passed since death. Because blow flies arrive earlier in the decomposition process, they provide the most accurate estimation of time since death. House flies (Musca domestica Linnaeus) are medically and forensically important flies. The aim of this study was to investigate time passed since death according to different stages of house fly life cycle with time variations over months of the year. Materials and methods: 120 mature male albino rats were used, 2 rats were scarified every 6 days and left exposed to houseflies, the different stages of the fly life cycle in relation to different postmortem intervals and represented time were recorded, photographed and statistically analyzed.
Results: There is a highly significant statistical difference between the duration of the presence  of the different stages housefly life cycle (eggs, 1st, 2nd, 3rd larval instars light colored (1^st stage) and dark colored pupae(2^nd stage) through different months of the year which was shorten in hot months of the year (August (9.6±1.57 h), July (1.5±0.52d), July (3.3±0.4d), August (7.6±0.69d), August (10.4±0.69d) and August (12.3±1.15d) respectively) and much prolonged in cold months of the year (January (27.2±2.85h) , January (3.6±0.51d), January (8.2±1.61d), Feb (14.1±1.52d), January (16.0±1.49d) , and January (21.2±1.22d) respectively).
The results showed that time after death could be estimated from certain forms of housefly stage and every stage denote the time with consideration to seasonal temperature state. There is statistically difference between the duration of the presence (p.m. interval) of the different stages of housefly life cycle through different months of the year which was shorten in hot months and much prolonged in cold months.Conclusion: postmortem interval could be determined through the presented forms of the housefly developmental stage in and around the dead body with consideration of presented date of observation.