Odour of the animal or human corpses immediately after death is very attractive for insects and other invertebrates. Blue and green bottle flies from the Calliphoridae family are the first colonizers of cadaver and immediately later necrophagous Diptera from the Sarcophagidae family settle on the same corpse. It is essential to determine the time past after death for elucidating the event in case of the homicide or suspicious death, and it is directly proportional to the post mortem interval expected time, which is based upon the speed of the larval growth. In this article, we purposed to stress the special interest of forensic entomology for the scientists who will apply this science in their forensic researches and case studies, and also to provide information to our judges, prosecutors and law enforcement agents in order to consider the entomological samples to be reliable and applicable evidences as biological stains and hairs. We are of the opinion that if any forensic entomologist is called to the crime scene or if the evidences are collected and then delivered to an entomologist, the forensic cases will be elucidated faster and more accurately.