Forensic entomology is a sub-discipline of entomology concerning insects and arthropods with their relationship to criminal investigations. Most important that comes out of it is the finding of an exact time of occurrence of a dead body by estimating the post-mortem interval (PMI). Our study focused on blow fly pupae, which are some of the earliest insects to colonize decomposing bodies. The pupae of the blow fly have the longest development period in the blow fly life history, but we have trouble viewing the inside of the pupae because of the puparium. It is, therefore, a developmental internal X-ray imaging stage carried out to see if such a division experiment could reveal a difference in growth based on temperatures in two different temperatures. All experiments were recorded accurately with an indoor Wi-Fi camera. Finally, the sampling individual in 20 degrees C and 30 degrees C shows a significant difference at the developmental time of 10,640 min and 5470 min, respectively. As the internal developmental stage at two different temperatures, it distinctly delimited based on their morphological characteristics. The internal developmental stages, identified by morphological characteristics, were subdivided into four distinct phases, improving the precision of post-mortem interval estimation. In this study, we attempted to delimit the pupae into developmental instars based on internal development with the help of X-ray imaging. More economical and easier than those currently in use, such as anatomical and micro-computed tomography. However, it is followed by collecting data through additional experiments at various temperatures to apply this method into actuality.