What is forensic entomology?

Forensic Entomology is the use of the insects, and their arthropod relatives that inhabit decomposing remains, to aid legal investigations.  The broad field of forensic entomology is commonly broken down into three general areas: medicolegal, urban, and stored product pests.  The medicolegal section focuses on the criminal component of the legal system and deals with the necrophagous (or carrion) feeding insects that typically infest human remains. The urban aspect deals with the insects that affect man and his immediate environment. This area has both criminal and civil components as urban pests may feed on both the living and the dead. The damage caused by their mandibles (or mouthparts) as they feed can produce markings and wounds on the skin of the living or deceased, which may be misinterpreted as prior abuse. Urban pests are of great economic importance and the forensic entomologist may become involved in civil proceedings over monetary damages to structures.  And, stored product insects are commonly found in foodstuffs and the forensic entomologist may serve as an expert witness during both criminal and civil proceedings involving food contamination.  The medicolegal aspect generally involves a determination some aspect of the postmortem interval.  Depending on the type of analysis and evidence provided to the forensic entomologist, this period of time may be termed the  minimum postmortem interval, the period of insect activity, or the time of colonization.  The terms do not necessarily refer to the same process, and the forensic investigator should have a discussion with the forensic entomologist about which term may be most appropriate for the case in question.

How diverse is forensic entomology?

In addition to aspects of the postmortem interval, the diverse applications of forensic entomology may include geographic origins, movement of the remains, traffic and transportation accidents, and the detection of abuse in children and neglect of the elderly.  Published cases exist that detail parents intentionally using wasps and bees to sting their children as a form of punishment.  Additionally, entomological evidence has been used to prove neglect and lack of proper care for wounds existing on the elderly under both private and institutional care.

It is theorized that the stings (or mere presence) of bees and wasps may be responsible for a large number of single occupant car accidents that seem to lack a definitive cause.  Some accident studies have shown insects to be within the top 20 causes of automobile accidents. In addition to automobile accidents, insects have been suspected of causing aircraft crashes through the obstruction of essential instrumentation, and even implicated in the obstruction of fuel lines causing engine failure.  Forensic entomologists are also requested to examine the fragmented remains of insects that have impacted and lodged on the front fascia, windshield, and radiator of automobiles.  Analysis of such remains can yield evidence to the probable path of an automobile through particular areas when pinpointing the location and areas of travel are of unique importance.

Insects can also affect the interpretation of blood spatter pattern analysis. Roaches simply walking through pooled and splattered blood will produce tracking that may not be readily recognizable to the untrained observer.  Specks of blood in unique and unusual areas (such as on ceilings) may mislead crime scene technicians unless they are aware of the appearance of blood contaminated roach tracks.  Similarly, flies and fleas may also track through pooled and spattered blood.  However, flies will also feed on the blood and then pass the partially digested blood in its feces, which are known as “flyspecks”.  Flies will also regurgitate and possibly drop a blood droplet on a remote surface, which may serve to confuse bloodstain analysis.  Fleas feeding on the living pass a large amount of undigested blood (used as the larval food source) on many household surfaces.  If a crime occurs in a heavily infected apartment, fecal drops already present would serve to confuse analysts as those droplets would test positive for human blood.  Therefore it is important to recognize and properly document the natural artifacts that may occur from the presence, feeding, and defecation of roaches, flies, and fleas.  Insects that feed on living, decomposing, or dried vegetable material are submitted to the forensic entomologist in an effort to determine the country or point of origin. This is particularly important with vegetative material such as imported cannabis.