Abstract Species belonging to the Muscidae family are important in the medical-sanitary and forensic fields due to their biology. The intrapuparial stage of Hydrotaea aenescens (Wiedemann, 1830), which represents about 50% of the immature development cycle in muscoid Diptera, has not yet been studied in detail. This study identifies and describes the main temporal morphological changes that occur in the pupal body of H. aenescens during its development at 22, 27, and 32 ± 1°C, RH 60 ± 10% with a 12-hr photoperiod. Ten pupae were collected, sacrificed, and fixed every 3 hr after pupariation up to 24 hr, and every 6 hr thereafter until the first emergence. Emergence took place at 282, 174, and 126 hr at 22, 27, and 32°C, with 520, 340, and 260 pupae, respectively. External morphology was described and recorded at eight development stages: pupariation, pre-pupae, early and late cryptocephalic pupae, phanerocephalic pupae, pupae-adult apolysis, pharate adults, and imago, employing 18 key morphological characters for pupae age. These morphological pupae characters, comprise, therefore an alternative and/or additional method to aid in determining the minimum Postmortem Interval (minPMI).