Insect Development and Forensic Entomology

When using insects as indicators of postmortem interval, two major approaches are possible. The first is to use the presence or absence of a species as an indicator of time of death, based on understandings of insect successional patterns. The second is to consider the degree of development for insects found on the cadaver. These approaches are complementary, although measuring insect development requires that immature insects are still present on the body. This latter approach depends on backtracking from the observed degree of development to the time of oviposition, to convert insect development into a time estimate. The time of death then can be estimated by adding the interval between death and ovi- position for the species in question (recognizing that various factors can influence initial oviposition). Measuring insect development is a powerful method for providing estimates of postmortem interval, but there are many crucial considerations and potential limitations in making such estimates. In this chapter we will explore these details of estimating insect development, and explore their implications for forensic entomology. Some general reviews on temperature and development include Wagner et al. (1984), Higley et al. (1986), and Higley and Peterson (1996), and Catts and Goff (1992) includes a discussion of age determination of maggots by temperature for forensic entomology.