Module 6 - Forensic Anthropology and Forensic Entomology (Bones & Bugs)

To find and convict a killer, it is often important to determine both when and how a victim died. The sites of blowfly or flesh fly infestation on a corpse may help to determine the cause of death or at least help in the reconstruction of events prior to death. Insect remains on a body can also be tested for foreign substances (such as drugs or toxins).

Usually, flies lay their eggs in the openings of the corpse, such as nose, eyes, ears, mouth, anus, and penis or vagina. Interestingly, forensic entomologists have found that flies tend to lay their eggs more often in the openings of the facial region than in the openings of the anogenital region (that is anus and penis or vagina). However, if a victim has been sexually assaulted prior to death and suffered from bleeding in the anogenital region during the attack, flies will likely infest these areas more than other body openings. Therefore, evidence of heavy fly colonization in the anogenital region of a body is evidence that a sex crime may have occurred.

Flies tend to lay their eggs in enclosed, moist locations such as body openings or open wounds. When heavy infestation of eggs and/or maggots are found in an area of the body where there is no apparent body opening (such as arms or legs), investigators may assume that trauma (such as a knife or bullet wound) has occurred at this site.

Not all homicide victims die from traumatic injuries. Some die of drug overdose or poisoning. Drugs and poisons can be traced in the blood, urine, stomach contents, hair, and nails of a victim’s body. The hair and nails of the dead do not decompose as quickly as the blood, urine, and stomach contents; therefore, they are reliable sites for testing for these deadly substances. These drugs and poisons can also be detected in the maggots and pupae that are found on human remains. Testing maggots and pupae for drugs and poisons is especially useful if the hair and nails of a victim are not found with the remains because various body parts are deposited in different locations or because certain body parts are consumed by an animal.

Using Forensic Entomology to Determine if a Body has been Moved after Death

In some forensic cases, the movement of the body may be traced using insects. If insects found upon a corpse are not native to the surroundings in which the body was found, it may be assumed that the individual was moved from one location to another. Insect parts or whole insects found upon evidence related to a homicide may be traced to their native locations. For example, insect parts or whole insects may be found within the interior of a suspect vehicle or in the tire treads of a suspect vehicle. These insects then could be traced by a forensic entomologist to a specific geographic location that could lead to a determination of where the suspect has been or where a victim’s body may be found.

The determination of the specific types of insect species found on human remains may also help to determine if a body has been moved or if it has remained in one location. For example, some fly species prefer to lay their eggs in warm, sunny places while other flies prefer to lay their eggs in shade. Some fly species are more common in cities while other fly species are found mostly in rural areas.