It is well known that certain types of insects gravitate toward corpses. Anyone who watches police procedural shows also knows that insects can provide useful evidence in murder cases. But few people know what types of evidence insects can provide to crime scene investigators. Obviously, insects are not useful as witnesses, as you don’t see insects taking the stand in court trials too often. But given how quickly certain insects gravitate toward new fresh corpses, understanding insect biology can allow a crime scene investigator to determine the time in which a person was killed.
Insects that gravitate toward corpses constitute a quasi-formal group of insects known as carrion insects. Surprisingly, carrion flies gravitate toward corpses that are less than a minute old. In fact, in many cases, numerous flies lay eggs on bodies in less than a minute following a person’s death. The first flies to lay eggs on a corpse are invaluable to investigators, as these eggs can determine time of death. Locating and assessing the age of the oldest fly eggs on a corpse allows investigators to determine the time that a person died with a high degree of accuracy.
Insects are also helpful in cases where murderers move a victim’s body from one area to another. This is because each particular landscape contains a very specific set of insects. If a person is killed in the dessert before being moved to a prairie, the desert-dwelling insects, their larvae and/or their eggs that remain on the body can tell investigators that the person was likely killed in the desert before being moved. The type of insects found on a corpse can indicate the elevation, landscape and environmental conditions of the particular region where a person was killed. In many cases, corpses found in rural areas are infested within urban-dwelling insects, indicating that murder victims are often killed in the city before being dumped in rural locations.
Most carrion insects prefer to nest and/or lay eggs within open wounds on a corpse. If open wounds are absent, insects gravitate toward body cavities, such as eye sockets, nose, ears, and the anus and genitals if they are exposed.
Have you ever found a variety of different insects gravitating toward the corpse of a dead animal?