Forensic entomology can be defined as the “application of the study of insects and other anthropods to legal issues” (wikipedia.org).  Urban, stored-product, and medicolegal are the three sub-categoris that make up forensic entomology.  However, for this purpose, I will be focusing upon the medicolegal application which deals directly with the insect’s role in the investigations of violent crimes.  One of the first recorded applications of forensic entomology came in France in 1848 when a workman discovered the mummified remains of a human baby behind a chimney.  Upon examination, Dr. Marcel Bergeret determined that due to the various insect traces, the infant had been placed there during the summer of 1848.  With this information, the French magistrates issued a warrant for the occupants of that residence during the alleged time period.  Although the doctor was mistaken about the actual time of death, this case still remains a classic example for the beginnings of forensic entomology.

Medicolegal entomology can be applied in many different forms.  It can be used to determine time and place of death, mode of death, whether the body was frozen or even wrapped after death.  Specific details such as larval weight, length, and succession are commonly used to narrow down the PMI, or rather Post Mortem Interval, which is the amount of time that has passed since death.  In homicide investigations this is crucial for determining when the individual died in order to track down the victims last moments of life, and last possible encounters.  It is also important to understand that the appearance of insects on a human body is not random.  Insect succession can be one of the best ways to determine a victims time of death.

“We have been struck by the fact that we have been the first to observe that the insects of cadavers, the workers of death, only arrive at their table successively, and always in the same order”.  The previous quote was written by Jean-Pierre Megnin, an entomologist at the Museum of Natural History in Paris.  The first arrivals, blowflies, can appear within hours, and in some cases, minutes of death.  Blowflies lay their eggs in wounds, on the eyes and lips, and in openings such as the mouth and vagina.  Within eight to fourteen hours, depending on temperature, the eggs hatch, and maggots emerge.  After the maggots leave the body and burrow in the ground for another twelve days until they emerge as flies.  During a murder investigation, it is crucial to dig up earth around the body to detect burrowed maggots and flies in order to determine PMI.  Other insects that play a role in the decomposition of a body include:  houseflies that feed on the decaying flesh; beetles, which enjoy the rotting tissue and maggots themselves; also parasitic wasps, scuttle flies, and cheese skippers’ help to break down tissues by feasting on left-over proteins.  After approximately six to twelve months, when there is no liquid matter left, mites will swarm the corpse, followed by hide-eating beetles.  Finally, clothes moths and spider beetles will consume any organic matter left.  Understanding the stages in which insects appear can assist in not only determining the time and cause of death, but its possible location as well.  Specific insects are inherent in different locations, and if those insects are present on the body, it can help to pinpoint the actual location of death.  When using forensic entomology in criminal investigations, it is also imperative that the proper method in handling such evidence is observed because vital information is often found inside the bodies of such insects.

There are two main insects that will be found when collecting samples of insects present on the body: flies and beetles.  These insects, however, will look very different at their many stages of progression.  In terms of flies, their stages involve: egg, larva, pupa, and adult.  Depending upon what stages the insects are presently in, and what location of the body they were collected from, an entomologist can begin to determine time of death, and wounds that may have been inflicted.  When collecting maggot specimens, they must first be placed in wate for ten to fifteen seconds that has been heated just below boiling point.  Next, the maggots are placed in 80% ethanol to preserve their sizes and color, in order to properly identify the maggots age.  Samples of eggs, adult flies, and beetles should also be collected for they can help to determine whether the body was moved after death, whether there were drugs in the victims system, or they may even be able to link another person to the scene of the crime.  In any case, several samples must be taken from the body, some should be preserved, while others should be transported alive.  Samples should also be gathered from the surrounding soil or carpet in order to gather any larva that may be buried.  Once all samples have been collected, an entomologist can begin to piece the puzzle together.

Forensic entomology is becoming increasing in popularity and has been used in hundreds of cases to determine time and place of death.  There are a handful of facilities that have dedicated themselves to the study of such investigations, one of the most famous being “The Body Farm”.  The Body Farm, also known as the University of Tennessee’s Anthropological Research Facility, spends it’s time investigating the effects of insects on human cadavers.  At their on-site research facility, The Body Farm has mapped the stages of entomology with bodies that are buried, exposed to air, submerged in water, locked in cars, and even buried in shallow graves under concrete.  Their research has helped to furter our understanding in the roles that insects play in the decomposition of human bodies.