Development rates were found to differ for protophormia terraenovae on the different rearing substrates, but not significantly in most cases; however, significant differences were found for the minimum development times to the adult and post-feeding stages. The significant difference to the adult stage can probably be explained by the significant difference between brain, heart, and muscle alone. A significant difference was found in the maximum development time on all substrates to the post-feeding stage only. This difference apparently results from the different rates between development on brain compared to development on muscle or heart. There were no significant differences for mode of development for any of the rearing substrates. If there are no wounds, the typical insect development occurs on the mucosal tissues of the face and genitalia. Under such circumstances, the brain tissue, and facial muscles will probably be consumed first. Thus, a combination of brain tissue and muscle may best represent the tissues consumed during development. Development may be completed at a different rate than what is currently assumed. In a death investigation, investigators seeking to determine time of death or placement of the body should always note where on the body the insects were collected. Future research should compare development rates for wounded compared with nonwounded substrates. The descriptions of materials and methods address the collection and replenishment of four separate stock insect colonies, the placement of the larvae on three rearing substrates, the nature and sources of the substrates, and the means and materials used in analyzing insect development. 3 figures, 3 tables, and 27 references