Abstract: 【Aim】 This study aims to examine the changing trend of puparium color and the pupal morphogenesis of Lucilia cuprina so as to provide relatively systematic pupal developmental data of this insect for the estimation of the postmortem interval (PMI). 【Methods】 Ten pupae were sampled at 12 h intervals from prepupa to emergence under natural conditions. The sampled pupae were fixed and observed， and the corresponding color indexes of puparium were collected and analyzed by digital image processing system. Then the pupae were dissected and their puparia were removed， and the external morphological changes of the pupae were observed and photographed under stereomicroscope. The morphological characteristics of pupae were described. 【Results】 The color of L. cuprina puparium gradually deepened with the developmental time， and obvious changes were observed at the beginning and final time of the pupal period. Based on the analyzed RGB indexes， a standard color plate of puparium was made. The pupal morphogenesis can be divided into eight stages， including cryptocephalic stage， phanerocephalic stage， brown thorax setae stage， tanned thorax setae stage， tanned abdomen setae stage， part pigmented eye stage， entire pigmented eye stage and preadult stage. 【Conclusion】 At the crime scene， the standard color plate of puparium can be used to preliminarily estimate the pupal stage through visual comparison， and based on the chronometrical morphology of L. cuprina pupae， the postmortem interval can be deduced.

Key words: Lucilia cuprina, forensic entomology, necrophagous insect, postmortem interval, pupa, morphogenesis, standard color plate