Jonathan S. Willett
Forensic entomology is the study of insects in a manner that is considered reliable for public or legal matters. A subcategory, medicolegal entomology, is focused primarily on the study of insects in connection to investigations of death. Sometimes referred to as “medical entomology” or “medicocriminal entomology,” medicolegal entomology is based on the premise that almost immediately following death, a corpse may begin to attract certain insects.
Many experts agree that the first recorded account in which entomology was used in a crime scene investigation was a 13th century murder case in China. After determining that a sickle may have been used in committing the murder, the village magistrate required all of the villagers to line up their sickles on the ground. One of the sickles, although apparently clean, attracted flies, while the others did not, prompting the owner of the sickle to confess to the crime.
Thereafter, important discoveries relating to medicolegal entomology were made by Francesco L. Redi, a 17th century Italian physician and Frenchman Bergeret d’Arbois in 19th century France. Although others subsequently used medicolegal entomology, it wasn’t widely recognized or accepted as a science until the 1950s and 1960s. Today, courts, legal professionals and law enforcement officers rely on such science. Two key facts that can be determined by medicolegal entomology include determining the location of the body at the time of death and the time of death.
Removal of Body
In homicide cases, the time of death and location of the body often differ. Medicolegal entomologists can help law enforcement find where the individual died by determining the species of insects found on the dead body and other clues. For instance, if a body is discovered indoors while covered with a type of insect that can only live and produce eggs in outdoor conditions, there is a clear indication that the body was moved. Equally important is noting what types of insects are not found on the corpse.
Time of Death
Time of death is especially important in criminal investigations to help police narrow their search for the perpetrator. In one case a dead body was found buried in a backyard of an individual, who had just moved to that home from another country. The individual was a suspect until it was determined by entomologists that the body had been there for years, which directed law enforcement suspicions to the home’s prior occupants.
Determining the time of death based on entomological data can be a complex matter. Many different factors and variables must be considered, such as the weight of any eggs found or the species of the fly that produced the eggs. Temperature is also a critical factor. For instance, the development of flies is often halted at certain cold temperatures, of which the threshold temperature is dependant on the species of fly. Despite such seemingly potentially ever-changing variables, this aspect of medicolegal entomology can be surprisingly precise.
To illustrate such accuracy, consider the following case conducted by M. Lee Goff, one of the few entomologists who specializes in death scene investigations: Goff’s data had indicated that a California homicide had occurred about two weeks prior, between the hours of 10 p.m. and midnight. When Goff had notified the authorities of his findings, they were stunned. Immediately prior to Goff’s phone call, a suspect had confessed to the killing, indicating that the killing was committed within the same two-hour time frame Goff estimated to be the time of death.
Other Uses of Forensic Entomology
- Forensic entomology has also been used to determine the presence and extent of termite infestation.
- In elder abuse cases, entomologists observe insects that accumulate around wounds. The study of the insects or maggots can reveal when the abuse occurred. Similar instances may occur in child neglect cases when diapers are not changed frequently enough.
- When law enforcement officers seize illegal drugs, such as marijuana, observing the type of insects present may assist in determining the origin of the drugs.