- Certain bugs used in forensics can determine time and manner of death.skeleton image by jeancliclac from Fotolia.com
A body with obvious signs of trauma lies abandoned in an open field. The only credible witnesses swarm the crime scene; however, they cannot testify without coaxing. The witnesses are none other than the critters who have arrived to feast on the remains, and any coaxing must occur with the capable manipulation of a forensic team within a laboratory setting.
Crime scene investigators, complete with their repertoire of medical examiners and forensic scientists, work in conjunction with law enforcement officials to determine exactly when a person ceased to exist. With the aid of specific bugs having predictable life cycles, investigators can determine how long ago a person died, called the postmortem interval (PMI), and whether the deceased had met with foul play.
- Forensic entomologists use life stages of the blowfly to determine the PMI.blowfly macro. image by mdb from Fotolia.com
Blowflies, attracted to foul stenches emanating from cadavers, usually discover dead bodies almost immediately after death. They lay eggs in body cavities such as the mouth, nose, ears and genital openings. Open wounds also attract the adult flies; consequently, the presence of maggots or larvae elsewhere on the body may signify a wound received immediatley before death, indicating foul play. The blowfly completes its entire life cycle between one to two weeks. By identifying the blowfly stages teeming on the body during the earlier stages of decomposition, investigators can determine fairly accurately how long ago a person died and possibly the manner in which he or she died.
- Carrion beetles feed on fly maggots present on a corpse. After gorging themselves on the larval feast, the beetles will lay their eggs on the cadaver. When the eggs hatch, the larvae feed on both the body and the maggots present. Carrion beetles typically will arrive a few days after the first flies, ensuring that maggots have had sufficient time to develop. The beetles remain until the maggots transform into adult flies. The fully developed carrion beetles leave the body after a few weeks.
- This beetle arrives at the corpse at a later stage of decomposition, not finding a home until five to 11 days after death and remaining in place until day 51 following death. The larvae, in contrast to the adult beetles, are more useful in determining the PMI since they forage only in bodies that already are dry, typically during the post-decay phase. The hide beetle completes its life cycle within 38 days if temperatures hover around an optimal 30 degrees Centigrade for the species. The beetles gently clean the bone of flesh, allowing forensic scientists to study the bones to identify gender, age and any traumatic damage to the bone.
Wasps and Bees
- A wasp sting can cause a deadly allergic reaction.wasp image by Henryk Olszewski from Fotolia.com
These insects typically cause problems for a forensic team since they feed on creatures such as flies and maggots that contribute to determination of the PMI. Bees and wasps can benefit forensic investigators in determining cause of death such as in cases in which the deceased has succumbed to a fatal allergic reaction to the poison in a sting. In another situation, a bee sting causing an allergic reaction may induce a driver to lose control of a vehicle, contributing to a collision. In several child abuse and homicide cases, parents have employed a multitude of wasps to sting a child to death within a locked room.