Background: The fleshfly Sarcophaga dux (Diptera;Sarcophagidae) is found in Indian Sub continent is of limited forensic significance as its poorly known larval development relationship with temperature and relative humidity. Objective: The objective of this study was to determine the effect of the temperature and relative humidity in the larval development of this fly in two seasons, Summer and Rain, so that the results of this study may enabling the forensic use of this fly in the estimation of Post Mortem Interval(PMI). Material and Method: The present study was carried out in the outer premises of the Regional Forensic Science Laboratory Building, Jagdalpur, Bastardist,Chhattishgarh, India. The fresh meat of male goat was used for rearing of larvae. The effect of temperature and relative humidity on the larval developmental time of this fly in two seasons, Rainy and Summer were studied in normal condition. Statistical analysis of variance was performed and standard significance level of P<0.05 was taken as standard. Results: The results of this study shown that in Rainy season it was completed in 264 h (11 days) when the average temperature ranged from 21.8°C to 24.5°C and the average humidity ranged from 79.5% to 95.5% where as in Summer it was completed in 528 hrs (22 days), when the temperature ranged from 26.5°C to 35.1°C and the humidity ranged from 34% to 67.5%. The P value was found to be P<<.05 in Temperature variation; andP<<0.05 in Humidity variation in different stages(1st instar larvae, 2nd instar larvae, 3rd instar larvae, Prepupae, Pupae and Adult). Conclusion: In the present study we have found that fluctuating temperature and relative humidity of outer condition in two seasons, Rainy and Summer effect the life cycle duration of the fly from the larvi position up to adult eclosion and statistical analysis has proved it to significant rejecting null hypothesis. This data can be further used in the estimation of Post Mortem Interval (PMI) in Homicide and Suspicious cases of both human and wild life poaching death cases.