In forensic entomology, the minimum postmortem interval (PMImin) estimative is usually based on the oldest immature recovered from a local of death. The time spent by fly immatures in the intrapuparial period comprises more than 50% of their complete life cycles. An accurate estimate of the duration of this period will improve PMImin estimates. The blow fly Hemilucilia semidiaphana (Rondani 1850) was found in six criminal cases in the city of Curitiba. Even though there is data on the morphology of the larval instars and developmental rate of H. semidiaphana, the intrapuparial period has not been investigated. Here, we provide a detailed description of the intrapuparial morphological changes of H. semidiaphana, which might be useful to estimate minimum PMI. Samples of H. semidiaphana in the intrapuparial period were obtained from immatures reared on an artificial diet in incubators adjusted to 25°C or 20°C temperature regimes. Blow fly puparia of H. semidiaphana were fixed at intervals of 3 and 6 h until emergence of the adult. The external morphological traits of sampled immatures were analyzed using light microscopy. Our analysis of the intrapuparial period of H. semidiaphana provided 21 traits from which nine were age informative. These nine characteristics divide the developmental time (144 h at 25°C and 192 h at 20°C) into smaller sections. The developmental data provided, together with the time line allows a practical way to make interspecific comparisons as well as to estimate the age of H. semidiaphana based on the intrapuparial development.