Forensic entomology is a branch of applied entomology that uses insects and other arthropods as a basis for legal evidence. Insects may be found on cadavers or elsewhere around crime scenes in the interest of forensic science. Forensic entomology is also used in cases of neglect and abuse of a property, as well as subjects of a toxicology analysis to detect drugs and incidents of food contamination. Therefore, forensic entomology is divided into three subfields: medico-legal/medico-criminal entomology, urban, and stored-product.
The field revolves around studying the types of insects commonly found in and on the place of interest (such as cadavers), their life cycles, their presence in different environments, and how insect assemblages change with the progression of decomposition (the process of "succession"). Insect assemblages can help approximate a body's primary location, as some insects are unique to specific areas. In medico-criminal cases, the primary goal is often to determine the postmortem interval (PMI; time since death) to aid in death investigations.
Insect succession patterns are identified based on the time a species spends in each developmental stage and the number of generations produced since the insect's introduction to a food source. By analyzing insect development alongside environmental data such as temperature, humidity, and vapor density, forensic entomologists can estimate the time since death, as flying insects are attracted to a body shortly after death. This field also provides clues about antemortem trauma and the displacement of a body after death.
Subfields Urban Urban forensic entomology typically concerns pest infestations in buildings, gardens, or other urban environments, and may be the basis of litigation between private parties and service providers such as landlords or exterminators. For instance, urban forensic entomology can be used to evaluate the efficiency of pest control techniques such as pesticide treatments, ascertaining the size of an infestation, and identifying the responsible party in situations involving infestations in rental homes. Urban forensic entomology can also assist in determining liability when stored goods, like grains or packaged foods, are contaminated with insects, helping to identify the infestation's origin. These techniques may be used in stored products cases where they can help to determine the chain of custody, when all points of possible infestation onset are examined to determine who is at fault.Bledsoe 2008, personal interview Moreover, environmental management and public health depend heavily on urban forensic entomology; researchers can track the transmission of disease carried by insects by examining insect populations in urban settings. Forensic techniques can also guide conservation efforts by evaluating the environmental effects of urbanization on insect populations.
Stored-product
Stored-product forensic entomology is often used in litigation over insect infestation or contamination of commercially distributed foods, including grains, flour, and packaged meals. Stored-product forensic entomologists may be asked to identify the species involved, evaluate the extent of an infestation, and pinpoint the infestation's source in a legal proceeding. They might also offer expert testimony about the circumstances that gave rise to the infestation and suggest safeguards to prevent similar risks in the future.
In general, forensic entomology of stored products adds both critical evidence to legal evaluation and contributes to overall food safety and quality assurances; forensic entomologists work to guarantee that food products are safe for consumption by identifying insect species and tracking their presence in stored goods. Additionally, this sector contributes to the general enhancement of food business practices by researching and developing novel techniques for pest management and product preservation.
Medico-legal Medico-legal forensic entomology involves the study of arthropods found at the scene of various incidents such as murder, suicide, rape, physical abuse, and the smuggling of contraband. This discipline provides the techniques to associate the victim(s), suspect(s), and scene together by identifying different arthropod species found in specific geographical locations. Forensic investigators can learn important details from insect activities, including the length of time passed since death (PMI), the presence of substances ― medicative or toxic ― in the body, and the movement or disturbance of the body following death. In murder investigations, forensic entomologists analyze the species of eggs which appear on the cadaver, their location on the body, and their development stage to determine the PMI and the location of death. The presence of specific insect species, which may be endemic (occurring only in certain places) or a well-defined phenology (active only at a certain season, or time of day). In association with other evidence, these can provide crucial links to times and locations where the criminal acts have occurred. Entomology can also aid when determining the time of an injury. One determining factor might be the observed species' preference of alimentation; when blowfly eggs laid on a hatch into the first larval instar (life stage), they require a liquid protein meal. Due to their minute size and fragility blowflies are unable to break through human skin themselves to attain this nutrition. Therefore, the female typically oviposits near a pre-existing wound or natural orifices to provide an accessible meal to her brood, such as blood, mucous, or other body fluids.
Another area covered by medico-legal forensic entomology is the relatively new field of entomotoxicology. This particular branch involves the testing of entomological specimens found at a scene for different drugs that may have possibly played a role in the death of the victim. The analytical perspective behind these methods relies upon the fact that the presence of drugs within the cadaver specifically affects the growth and morphology of the insects ingesting those toxins from the corpse. Due to these alterations, the presence of drugs can potentially lead to an erroneous PMI when basing it on the abnormal physical development of insects who have fed on them.
Myiasis
Myiasis, the infestation of living vertebrate animals with certain species of dipteran larvae (ex: blowfly maggots), is a phenomenon that may be noted in cases of abandonment or neglect. This condition occurs when flies colonize a living human or animal, feeding on the organism's accessible living tissues, ingesting food or bodily fluids. In a forensic context, myasis can be confusing, as it may indicate the time of neglect or injury rather than PMI if the remains were colonized when alive. This highlights the importance of careful interpretation of all evidence in forensic investigation.
History Historically, several accounts of applications have been for, and experimentation with, forensic entomology. Along with an initial case report in China from the 13th century, the primitive observation and correlation between arthropods and forensic contexts has been documented in Germany and France. This observation was conducted during a mass exhumation in the late 1880s by Hofmann and Reinhard. However, only in the last 30 years has forensic entomology been systematically explored as a feasible source for evidence in criminal investigations. Through documented experiments and focus on arthropods and death, the works of Sung Tzu, Francesco Redi, Bergeret d'Arbois, Jean Pierre Mégnin and the physiologist Hermann Reinhard form the foundations for today's modern forensic entomology.
Over time, the study of forensic entomology evolved from an esoteric science reserved only for entomologists and forensic scientists. Early twentieth-century popular scientific literature began to pique a broader interest in entomology. The very popular ten-volume book series, Alfred Brehem's Thierleben (Life of Animals, 1876–1879) expounded on many zoological topics, including the biology of arthropods. The accessible writing style of French entomologist Jean-Henri Fabre was also instrumental to the popularization of entomology. His collection of writings Souvenirs Entomologique, written during the last half of the 19th century, is especially useful because of the meticulous attention to detail to the observed insects' behaviors and life cycles.
Song Ci
Song Ci (sometimes called Sung Tzu) was a Song dynasty-era (960–1279) judicial intendant and polymath writer who lived in China from 1188 to 1251 AD. He wrote a book titled Washing Away of Wrongs/Collected Cases of Injustice Rectified in 1247 AD, which was intended as a handbook for criminal investigators and coroners so that they may assess a crime scene effectively; it subsequently became the earliest recorded account of someone using forensic entomology for judicial means. Here he depicts several cases in which he took notes on how a person died and determining the probable cause. He also explains in detail how to examine a corpse before and after burial. The level of detail in his explanations of all his cases laid down the fundamentals for modern forensic entomologists. In one murder case dated 1235, a villager was stabbed to death and authorities determined that his wounds were inflicted by a sickle, a tool used for cutting rice at harvest time, a fact which led them to suspect a fellow peasant worker was involved. The local magistrate had the villagers assemble in the town square, where they would temporarily relinquish their sickles. Within minutes, a swarm of blow flies gathered around one sickle and no others, attracted to traces of blood unseen by the naked eye. It became apparent to all that the owner of that sickle was the culprit, the latter pleading for mercy as authorities detained him.
Francesco Redi
In 1668, Italian physician Francesco Redi disproved the theory of spontaneous generation, which was the accepted theory of Redi's day; it claimed that maggots developed spontaneously (without any visible cause) from rotting meat. In an experiment, Redi used samples of rotting meat that were either fully exposed to the air, partially exposed to the air, or isolated from the air. Redi showed that both fully and partially exposed rotting meat bore maggots whereas rotting meat not exposed to air did not develop maggots; this discovery completely changed how people viewed the process of decomposition and prompted further investigations into insect life cycles and entomology in general.
Bergeret d'Arbois
Dr. Louis François Etienne Bergeret (1814–1893) was a French physician and was the first to apply forensic entomology to a case. In a case report published in 1855, he stated a general life cycle for insects and made many assumptions about their mating habits. Nevertheless, these assumptions led him to the first application of forensic entomology in an estimation of post-mortem interval (PMI). His report used forensic entomology as a tool to prove his hypothesis on how and when the person had died.
Hermann Reinhard
The first systematic study in forensic entomology was conducted in 1881 by German doctor Hermann Reinhard. He exhumed many bodies and demonstrated that the development of many different insect species could be tied to buried bodies. Reinhard conducted his first study in Eastern Germany and collected many Phorid flies there. He concluded that the development of some, but not all species, of insects were associated directly with decaying flesh since there were 15-year-old beetles who had little direct contact with the bodies. Reinhard's works and studies were used extensively in further forensic entomology studies.
Jean Pierre Mégnin