Forensic entomology

Forensic entomology applies knowledge of insects and their life cycles to legal investigations. Its best-known role is in death investigations, but entomologists also give evidence in civil cases, for instance about insects in stored food or infestations in buildings, and in cases of neglect, where maggots in wounds or soiled clothing show how long a person went without care.

After death, blow flies usually arrive first, sometimes within minutes, drawn by the smells of decay. Females lay eggs in wounds and moist openings; the maggots that hatch feed and pass through three larval stages, or instars, then pupate and emerge as adults. Because this development runs at a predictable, temperature-dependent pace, an expert who identifies the species and the oldest stage present, and reconstructs the temperatures at the scene, can estimate the least time since eggs were first laid. This minimum postmortem interval is especially useful days after death, when cooling and rigor mortis no longer help, and over the following weeks beetles and other insects arrive in a broadly predictable order.

Estimates must allow for anything that delays insects, such as burial, wrapping, cold or rain, and for drugs in the body, which can speed or slow larval growth. The species present can also show that a body was moved.